Ca2+ transients in cardiac myocytes measured with high and low affinity Ca2+ indicators.
AuthorsBerlin JR,Konishi M
JournalBiophysical journal
PubMed ID8274651
Intracellular calcium ion ([Ca2+]i) transients were measured in voltage-clamped rat cardiac myocytes with fura-2 or furaptra to quantitate rapid changes in [Ca2+]i. Patch electrode solutions contained the K+ salt of fura-2 (50 microM) or furaptra (300 microM). With identical experimental conditions, peak amplitude of stimulated [Ca2+]i transients in furaptra-loaded myocytes ... More
Assembly of the nuclear pore: biochemically distinct steps revealed with NEM, GTP gamma S, and BAPTA.
AuthorsMacaulay C, Forbes DJ
JournalJ Cell Biol
PubMed ID8567730
A key event in nuclear formation is the assembly of functional nuclear pores. We have used a nuclear reconstitution system derived from Xenopus eggs to examine the process of nuclear pore assembly in vitro. With this system, we have identified three reagents which interfere with nuclear pore assembly, NEM, GTP ... More
Evidence for role of cytosolic free calcium in hypoxia-induced proximal tubule injury.
AuthorsKribben A, Wieder ED, Wetzels JF, Yu L, Gengaro PE, Burke TJ, Schrier RW
JournalJ Clin Invest
PubMed ID8182125
The role of cytosolic free Ca2+ ([Ca2+]i) in hypoxic injury was investigated in rat proximal tubules. [Ca2+]i was measured using fura-2 and cell injury was estimated with propidium iodide (PI) in individual tubules using video imaging fluorescence microscopy. [Ca2+]i increased from approximately 170 to approximately 390 nM during 5 min ... More
Mechanism of inhibition of polypeptide chain initiation in calcium-depleted Ehrlich ascites tumor cells.
AuthorsKumar RV, Wolfman A, Panniers R, Henshaw EC
JournalJ Cell Biol
PubMed ID2500444
Protein synthesis in Ehrlich ascites tumor cells is inhibited when cellular calcium is depleted by the addition of EGTA to the growth medium. This inhibition is at the level of polypeptide chain initiation as evidenced by a disaggregation of polyribosomes accompanied by a significant elevation in 80-S monomers. To identify ... More
Role of diacylglycerol kinase alpha in the attenuation of receptor signaling.
AuthorsSanjuán MA, Jones DR, Izquierdo M, Mérida I
JournalJ Cell Biol
PubMed ID11285286
'Diacylglycerol kinase (DGK) is suggested to attenuate diacylglycerol-induced cell responses through the phosphorylation of this second messenger to phosphatidic acid. Here, we show that DGKalpha, an isoform highly expressed in T lymphocytes, translocates from cytosol to the plasma membrane in response to two different receptors known to elicit T cell ... More
Protein kinase inhibitors prevent junction dissociation induced by low extracellular calcium in MDCK epithelial cells.
AuthorsCiti S
JournalJ Cell Biol
PubMed ID1556151
'When epithelial cell cultures are transferred from a medium with a normal extracellular calcium concentration (1-2 mM) to a medium with a low extracellular calcium concentration (LC, less than 50 microM free Ca2+) cell-cell contacts are disrupted, and the tight junction-dependent transepithelial resistance drops. In this study, I used MDCK ... More
Microtubules regulate local Ca2+ spiking in secretory epithelial cells.
AuthorsFogarty KE, Kidd JF, Turner A, Skepper JN, Carmichael J, Thorn P
JournalJ Biol Chem
PubMed ID10801885
'The role of the cytoskeleton in regulating Ca(2+) release has been explored in epithelial cells. Trains of local Ca(2+) spikes were elicited in pancreatic acinar cells by infusion of inositol trisphosphate through a whole cell patch pipette, and the Ca(2+)-dependent Cl(-) current spikes were recorded. The spikes were only transiently ... More
A role for calcium in stabilizing transport vesicle coats.
Authors Ahluwalia J P; Topp J D; Weirather K; Zimmerman M; Stamnes M;
JournalJ Biol Chem
PubMed ID11435443
'Calcium has been implicated in regulating vesicle fusion reactions, but its potential role in regulating other aspects of protein transport, such as vesicle assembly, is largely unexplored. We find that treating cells with the membrane-permeable calcium chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N'',N''-tetraacetic acid tetrakis(acetoxymethyl ester) (BAPTA-AM), leads to a dramatic redistribution of the vesicle ... More
Evidence that Ca(2+) cycling by the plasma membrane Ca(2+)-ATPase increases the 'excitability' of the extracellular Ca(2+)-sensing receptor.
AuthorsDe Luisi A, Hofer AM
JournalJ Cell Sci
PubMed ID12640037
'The extracellular Ca(2+)-sensing receptor (CaR) is a widely expressed G-protein-coupled receptor that translates information about [Ca(2+)] in the extracellular milieu to the interior of the cell, usually via intracellular Ca(2+) signaling pathways. Using fura-2 imaging of cytoplasmic [Ca(2+)], we observed that HEK293 cells expressing CaR oscillated readily under conditions permissive ... More
Muscarinic acetylcholine receptor-mediated induction of zif268 mRNA in PC12D cells requires protein kinase C and the influx of extracellular calcium.
AuthorsEbihara T, Saffen D
JournalJ Neurochem
PubMed ID9048745
'The immediate-early gene zif268 (egr-1, NGFI-A, krox-24) encodes a transcription factor that has been proposed to play a role in differentiation and neuronal plasticity. zif268 mRNA is undetectable in unstimulated PC12D cells, a subline of PC12 characterized by accelerated differentiation in the presence of nerve growth factor, but is rapidly ... More
Differences in Ca2+ buffering properties between excitatory and inhibitory hippocampal neurons from the rat.
AuthorsLee SH, Rosenmund C, Schwaller B, Neher E
JournalJ Physiol
PubMed ID10835043
'Endogenous calcium binding ratios (kappaS) in dendrites of cultured hippocampal neurons were estimated according to the single compartment model for transients in intracellular Ca2+ concentration ([Ca2+]). In addition, the electrophysiological characteristics of neurons were classified by their autaptic currents and intrinsic firing patterns. These data were analysed in order to ... More
Lipid factor (bVLF) from bovine vitreous body evokes in EGFR-T17 cells a Ca2+-dependent K+ current associated with inositol 1,4,5-trisphosphate-independent Ca2+ mobilization.
'Bovine vitreous lipid factor (bVLF) is a complex phospholipid isolated from bovine vitreous body with strong Ca(2+)-mobilizing activity. In this study, the effects of bVLF on membrane potential were investigated in EGFR-T17 fibroblasts with the whole-cell patch clamp technique on monolayer cells, as well as with the fluorescent dye bis-oxonol ... More
G protein-coupled receptors mediate a fast excitatory postsynaptic current in CA3 pyramidal neurons in hippocampal slices.
AuthorsMiller LD, Petrozzino JJ, Connor JA
JournalJ Neurosci
PubMed ID8613765
'Synaptic activation in the presence of competitive (D,L-APV,CNQX) and noncompetitive (MK-801,GYKI-52466) ionotropic glutamate receptor antagonists induced fast (10-90% rise time of 15-30 msec) postsynaptic responses in CA3 pyramidal neurons from acute and cultured hippocampal slices. Postsynaptic currents were studied extensively in slice cultures, and displayed a linear current-voltage relationship, with ... More
An inositol 1,4,5-trisphosphate receptor-gated intracellular Ca(2+) store is involved in regulating sperm hyperactivated motility.
AuthorsHo HC, Suarez SS
JournalBiol Reprod
PubMed ID11673282
'Hyperactivated motility, a swimming pattern displayed by mammalian sperm in the oviduct around the time of ovulation, is essential to fertilization. Ca(2+) has been shown to be crucial for the initiation and maintenance of hyperactivated motility. Nevertheless, how Ca(2+) reaches the axoneme in the core of the flagellum to switch ... More
Effect of intracellular pH on cytosolic free [Ca2+] in human epidermoid A-431 cells.
AuthorsKiang JG
JournalEur J Pharmacol
PubMed ID1664334
'This study characterizes the correlation between intracellular pH (pHi) and the cytosolic free Ca2+ concentration ([Ca2+]i) in suspended and adherent human epidermoid A-431 cells. Using the fluorescent dyes 2,7-bis(carboxyethyl)carboxyfluorescein acetoxymethyl ester (BCECF) and fura-2, the resting pHi and [Ca2+]i in suspended cells were 7.23 +/- 0.03 and 209 +/- 30 ... More
Ca(2+)-dependent block and potentiation of L-type calcium current in guinea-pig ventricular myocytes.
AuthorsBates SE, Gurney AM
JournalJ Physiol
PubMed ID8410697
'1. The caged calcium compound nitr-5 has been used to investigate the response of the L-type calcium current (ICa) of guinea-pig ventricular cells to a rapid increase in the free intracellular calcium concentration ([Ca2+]i). 2. When 2 mM nitr-5 or 3 mM DM-nitrophen was loaded into cells via a patch ... More
Regulation of the cardiac ryanodine receptor channel by luminal Ca2+ involves luminal Ca2+ sensing sites.
AuthorsGyörke I, Györke S
JournalBiophys J
PubMed ID9826602
'The mechanism of activation of the cardiac calcium release channel/ryanodine receptor (RyR) by luminal Ca2+ was investigated in native canine cardiac RyRs incorporated into lipid bilayers in the presence of 0.01 microM to 2 mM Ca2+ (free) and 3 mM ATP (total) on the cytosolic (cis) side and 20 microM ... More
Photophysics of the fluorescent Ca2+ indicator Fura-2.
AuthorsVan den Bergh V, Boens N, De Schryver FC, Ameloot M, Steels P, Gallay J, Vincent M, Kowalczyk A
JournalBiophys J
PubMed ID7756530
'The photophysics of the complex forming reaction of Ca2+ and Fura-2 are investigated using steady-state and time-resolved fluorescence measurements. The fluorescence decay traces were analyzed with global compartmental analysis yielding the following values for the rate constants at room temperature in aqueous solution with BAPTA as Ca2+ buffer: k01 = ... More
Coordination between Ca2+ release and subsequent re-uptake in the sarcoplasmic reticulum.
AuthorsSaiki Y, Ikemoto N
JournalBiochemistry
PubMed ID10074365
'We here report the results of our recent effort to produce, in the isolated sarcoplasmic reticulum (SR), a biphasic Ca2+ release and Ca2+ re-uptake transient and to resolve the kinetic relationship between Ca2+ release and re-uptake of the released Ca2+. Ca2+ release from the SR was induced by polylysine (the ... More
Stable association between G alpha(q) and phospholipase C beta 1 in living cells.
AuthorsDowal L, Provitera P, Scarlata S
JournalJ Biol Chem
PubMed ID16754659
'Signal transduction through G alpha(q) involves stimulation of phospholipase C beta (PLC beta) that results in increased intracellular Ca2+ and activation of protein kinase C. We have measured complex formation between G alpha(q) and PLC beta1 in vitro and in living PC12 and HEK293 cells by fluorescence resonance energy transfer. ... More
Calcium permeability of the neuronal nuclear envelope: evaluation using confocal volumes and intracellular perfusion.
AuthorsO'Malley DM
JournalJ Neurosci
PubMed ID7931542
'In many calcium-imaging studies, the nuclear envelope appears to maintain a gradient of free calcium between the nucleus and cytosol. This issue was examined by loading amphibian sympathetic neurons with the calcium indicator fluo 3 via whole-cell patch clamping. Confocal optical sectioning allowed acquisition of independent calibration curves for the ... More
Nuclei from fertilized mouse embryos have calcium-releasing activity.
AuthorsKono T, Carroll J, Swann K, Whittingham DG
JournalDevelopment
PubMed ID7743925
'During mammalian fertilization, the sperm triggers a series of intracellular Ca2+ oscillations which initiate oocyte activation and the formation of pronuclei. Oocyte activation can be induced artificially by a variety of chemical and physical stimuli which elevate intracellular calcium. We show that the transfer of nuclei from 1- and 2-cell-stage ... More
Alien intracellular calcium chelators attenuate neurotransmitter release at the squid giant synapse.
'A number of calcium buffers were examined for their ability to reduce evoked transmitter release when injected into the presynaptic terminal of the squid giant synapse. Injection of EGTA was virtually ineffective at reducing transmitter release, even at estimated intracellular concentrations up to 80 mM. Conversely, the buffer 1,2-bis(2-aminophenoxy)ethane-N,N,N'',N''-tetraacetic acid ... More
Class A scavenger receptor up-regulation in smooth muscle cells by oxidized low density lipoprotein. Enhancement by calcium flux and concurrent cyclooxygenase-2 up-regulation.
AuthorsMietus-Snyder M, Gowri MS, Pitas RE
JournalJ Biol Chem
PubMed ID10837497
'Oxidative stress caused by phorbol esters or reactive oxygen up-regulates the class A scavenger receptor (SR-A) in human smooth muscle cells (SMC), which normally do not express this receptor. The increase in SR-A expression correlates with activation of the redox-sensitive transcription factors activating protein-1 c-Jun and CCAAT enhancer-binding protein beta. ... More
AuthorsDella Rocca GJ, Mukhin YV, Garnovskaya MN, Daaka Y, Clark GJ, Luttrell LM, Lefkowitz RJ, Raymond JR
JournalJ Biol Chem
PubMed ID9988712
'Many receptors that couple to heterotrimeric guanine nucleotide-binding (G) proteins mediate rapid activation of the mitogen-activated protein kinases, Erk1 and Erk2. The Gi-coupled serotonin (5-hydroxytryptamine (5-HT)) 5-HT1A receptor, heterologously expressed in Chinese hamster ovary or human embryonic kidney 293 cells, mediated rapid activation of Erk1/2 via a mechanism dependent upon ... More
Thapsigargin activates a calcium influx pathway in the unfertilized mouse egg and suppresses repetitive calcium transients in the fertilized egg.
AuthorsKline D, Kline JT
JournalJ Biol Chem
PubMed ID1387638
'At fertilization, the sperm initiates development of the mouse egg by inducing a large transient increase in the intracellular Ca2+ concentration ([Ca2+]i), which is followed by repetitive transient increases in [Ca2+]i. To determine how the repetitive Ca2+ transients are produced, thapsigargin, an inhibitor of the endoplasmic reticulum Ca-ATPase, was used ... More
Lipopolysaccharide-mediated signal transduction through phospholipase D activation in monocytic cell lines.
AuthorsNatarajan V, Iwamoto GK
JournalBiochim Biophys Acta
PubMed ID8011674
'Lipopolysaccharide (LPS)-induced phospholipase D (PLD) activation was investigated in undifferentiated monocytic leukemic cell lines THP-1 and U-937. Treatment of THP-1 or U-937 cells labelled with [32P]orthophosphate, [32P]acyl GPC or [3H]alkyl GPC with LPS, in the presence of 0.5% ethanol, resulted in the accumulation of labelled phosphatidylethanol (PEt) through PLD activation. ... More
An active motor model for adaptation by vertebrate hair cells.
AuthorsAssad JA, Corey DP
JournalJ Neurosci
PubMed ID1527581
'Bullfrog saccular hair cells adapt to maintained displacements of their stereociliary bundles by shifting their sensitive range, suggesting an adjustment in the tension felt by the transduction channels. It has been suggested that steady-state tension is regulated by the balance of two calcium-sensitive processes: passive "slipping" and active "tensioning." Here ... More
Examination of TEA-induced synaptic enhancement in area CA1 of the hippocampus: the role of voltage-dependent Ca2+ channels in the induction of LTP.
AuthorsHuang YY, Malenka RC
JournalJ Neurosci
PubMed ID8381168
'The role of voltage-dependent Ca2+ channels (VDCCs) in the induction of long-term potentiation (LTP) in the CA1 region of rat hippocampus was determined by examining the relationship between LTP and the long-lasting synaptic enhancement induced by extracellular application of tetraethylammonium (TEA). Consistent with previous findings (Aniksztejn and Ben-Ari, 1991), the ... More
Capacitative Ca2+ entry is closely linked to the filling state of internal Ca2+ stores: a study using simultaneous measurements of ICRAC and intraluminal [Ca2+].
AuthorsHofer AM, Fasolato C, Pozzan T
JournalJ Cell Biol
PubMed ID9442108
'ICRAC (the best characterized Ca2+ current activated by store depletion) was monitored concurrently for the first time with [Ca2+] changes in internal stores. To establish the quantitative and kinetic relationship between these two parameters, we have developed a novel means to clamp [Ca2+] within stores of intact cells at any ... More
Ca2+ binding to sarcoplasmic reticulum ATPase revisited. I. Mechanism of affinity and cooperativity modulation by H+ and Mg2+.
AuthorsForge V, Mintz E, Guillain F
JournalJ Biol Chem
PubMed ID8496159
'H+ and Mg2+ are known to inhibit Ca2+ binding to the transport sites of sarcoplasmic reticulum-ATPase. Evaluation of the affinity for the Ca2+ binding sites requires measurement of the amount of Ca2+ bound to ATPase as a function of the free Ca2+ concentration imposed by a Ca2+ chelator. The choice ... More
Phosphatidylinositol 3-kinase-dependent extracellular calcium influx is essential for CX(3)CR1-mediated activation of the mitogen-activated protein kinase cascade.
'Fractalkine, the first member of the CX(3)C chemokine family, induces leukocyte chemotaxis through activation of its high affinity receptor, CX(3)CR1. Like other chemokine receptors, CX(3)CR1 is coupled to a pertussis toxin-sensitive heterotrimeric G(i) protein, which is necessary for rapid rise in the concentration of intracellular calcium. Using a Chinese hamster ... More
Buffer kinetics shape the spatiotemporal patterns of IP3-evoked Ca2+ signals.
AuthorsDargan SL, Parker I
JournalJ Physiol
PubMed ID14555715
'Ca2+ liberation through inositol 1,4,5-trisphosphate receptors (IP3Rs) plays a universal role in cell regulation, and specificity of cell signalling is achieved through the spatiotemporal patterning of Ca2+ signals. IP3Rs display Ca2+-induced Ca2+ release (CICR), but are grouped in clusters so that regenerative Ca2+ signals may remain localized to individual clusters, ... More
Calcium can disrupt the SNARE protein complex on sea urchin egg secretory vesicles without irreversibly blocking fusion.
'The homotypic fusion of sea urchin egg cortical vesicles (CV) is a system in which to correlate the biochemistry and physiology of membrane fusion. Homologues of vesicle-associated membrane protein (VAMP), syntaxin, and SNAP-25 were identified in CV membranes. A VAMP and syntaxin immunoreactive band at a higher apparent molecular mass ... More
Calcium signalling in sarcoplasmic reticulum, cytoplasm and mitochondria during activation of rabbit aorta myocytes.
AuthorsGurney AM, Drummond RM, Fay FS
JournalCell Calcium
PubMed ID11013464
'This study investigated the relationship between cytoplasmic, mitochondrial, and sarcoplasmic reticulum (SR) [Ca(2+)] in rabbit aorta smooth muscle cells, following cell activation. Smooth muscle cells were loaded with the Ca(2+)-sensitive fluorescent indicator Mag-Fura-2-AM, and then either permeabilized by exposure to saponin, or dialyzed with a patch pipette in the whole-cell ... More
The motility of demembranated human spermatozoa is inhibited by free calcium ion activities of 500 nmol/L or more.
AuthorsWilliams KM, Ford WC
JournalInt J Androl
PubMed ID11454073
'A number of studies have demonstrated that high calcium ion activities inhibit sperm motility, but little is known about the effect of different calcium activities close to the physiological range. Therefore, we investigated whether raising calcium activities within the submicromolar range would inhibit the motility of demembranated human spermatozoa. Spermatozoa ... More
Inactivation kinetics of calcium current of acutely dissociated CA1 pyramidal cells of the mature guinea-pig hippocampus.
AuthorsKay AR
JournalJ Physiol
PubMed ID1653853
'1. The process of inactivation of the Ca2+ current of acutely dissociated pyramidal cells from the CA1 subfield of mature guinea-pig hippocampus was characterized. The decline of the current after rapid activation could be approximated well by the sum of two exponentials (time constants approximately 200 ms and 2 s) ... More
Chemical depolarization-induced SR calcium release in triads isolated from rabbit skeletal muscle.
AuthorsIkemoto N, Yano M, el-Hayek R, Antoniu B, Morii M
JournalBiochemistry
PubMed ID8086413
'Excitation-Ca2+ release coupling properties in the heavy microsomal fraction of the rabbit skeletal muscle enriched in triads were investigated by following the same type of approach used for the studies of excitation-contraction coupling in the skinned fiber system. Incubation of the triads with Mg-ATP in a solution containing 150 mM ... More
Synaptic excitation produces a long-lasting rebound potentiation of inhibitory synaptic signals in cerebellar Purkinje cells.
AuthorsKano M, Rexhausen U, Dreessen J, Konnerth A
JournalNature
PubMed ID1313949
'Persistent changes in synaptic efficacy are thought to underlie the formation of learning and memory in the brain. High-frequency activation of an afferent excitatory fibre system can induce long-term potentiation, and conjunctive activation of two distinct excitatory synaptic inputs to the cerebellar Purkinje cells can lead to long-term depression of ... More
Modulation of L-type Ca2+ current by fast and slow Ca2+ buffering in guinea pig ventricular cardiomyocytes.
AuthorsYou Y, Pelzer DJ, Pelzer S
JournalBiophys J
PubMed ID8994602
'Free Ca2+ near Ca2+ channel pores is expected to be lower in cardiomyocytes dialyzed with bis-(o-amino-phenoxy)-ethane-N,N,N'',N''-tetraacetic acid (BAPTA) than with ethyleneglycol-bis-(beta-aminoethyl)-N,N,N'',N''-tetraacetic acid (EGTA) because BAPTA chelates incoming Ca2+ more rapidly. The consequences of intracellular Ca2+ buffering by BAPTA (0.2-60 mM) and by EGTA (0.2-67 mM) on whole-cell L-type Ca2+ current ... More
Signaling pathways underlying muscarinic receptor-induced [Ca2+]i oscillations in HEK293 cells.
AuthorsLuo D, Broad LM, Bird GS, Putney JW
JournalJ Biol Chem
PubMed ID11096083
'We have investigated the signaling pathways underlying muscarinic receptor-induced calcium oscillations in human embryonic kidney (HEK293) cells. Activation of muscarinic receptors with a maximal concentration of carbachol (100 microm) induced a biphasic rise in cytoplasmic calcium ([Ca2+]i) comprised of release of Ca2+ from intracellular stores and influx of Ca2+ from ... More
Monitoring calcium in turtle hair cells with a calcium-activated potassium channel.
AuthorsTucker TR, Fettiplace R
JournalJ Physiol
PubMed ID8865061
'1. An apamin-sensitive Ca(2+)-activated K+ channel was characterized in turtle hair cells and utilized to monitor submembranous intracellular Ca2+ and to evaluate the concentration of the mobile endogenous calcium buffer. 2. Isolated hair cells were voltage clamped with whole-cell patch electrodes filled with a Cs(+)-based intracellular solution to block the ... More
Effect of intracellular injection of inositol trisphosphate on cytosolic calcium and membrane currents in Aplysia neurons.
AuthorsLevy S
JournalJ Neurosci
PubMed ID1607931
'Pacemaker cells of Aplysia californica display a regular bursting that results from a complex interplay of Ca(2+)-mediated conductances and a continuous influx and extrusion of Ca2+. The effect of the second messenger 1,4,5-inositol trisphosphate (InsP3) on intracellular free Ca2+ concentration (Cai) regulation and electrical properties was investigated in identified neurons ... More
Regulation of anaphase chromosome motion in Tradescantia stamen hair cells by calcium and related signaling agents.
AuthorsZhang DH, Callaham DA, Hepler PK
JournalJ Cell Biol
PubMed ID2114409
'Several lines of evidence support the idea that increases in the intracellular free calcium concentration [( Ca2+]i) regulate chromosome motion. To directly test this we have iontophoretically injected Ca2+ or related signaling agents into Tradescantia stamen hair cells during anaphase and measured their effect on chromosome motion and on the ... More
Intracellular pH regulates basolateral K+ and Cl- conductances in colonic epithelial cells by modulating Ca2+ activation.
AuthorsChang D, Kushman NL, Dawson DC
JournalJ Gen Physiol
PubMed ID1719125
'The role of intracellular pH as a modulator of basolateral K+ and Cl- conductances in epithelial cells was studied using digitonin-permeabilized colonic cell layers so that cytosolic pH could be clamped at specific values, while basolateral K+ and Cl- conductances were activated by stepwise increases in intracellular free Ca2+. Increasing ... More
The bell-shaped Ca2+ dependence of the inositol 1,4, 5-trisphosphate-induced Ca2+ release is modulated by Ca2+/calmodulin.
AuthorsMissiaen L, Parys JB, Weidema AF, Sipma H, Vanlingen S, De Smet P, Callewaert G, De Smedt H
JournalJ Biol Chem
PubMed ID10318777
'Calmodulin inhibits inositol 1,4,5-trisphosphate (IP3) binding to the IP3 receptor in both a Ca2+-dependent and a Ca2+-independent way. Because there are no functional data on the modulation of the IP3-induced Ca2+ release by calmodulin at various Ca2+ concentrations, we have studied how cytosolic Ca2+ and Sr2+ interfere with the effects ... More
Metabolism of inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate by the oocytes of Xenopus laevis.
AuthorsSims CE, Allbritton NL
JournalJ Biol Chem
PubMed ID9461597
'The pathway and kinetics of inositol 1,4,5-trisphosphate (IP3) metabolism were measured in Xenopus laevis oocytes and cytoplasmic extracts of oocytes. Degradation of microinjected IP3 in intact oocytes was similar to that in the extracts containing comparable concentrations of IP3 ([IP3]). The rate and route of metabolism of IP3 depended on ... More
Activation of a recombinant petunia glutamate decarboxylase by calcium/calmodulin or by a monoclonal antibody which recognizes the calmodulin binding domain.
AuthorsSnedden WA, Koutsia N, Baum G, Fromm H
JournalJ Biol Chem
PubMed ID8626755
'To date, only plants have been shown to possess a form of glutamate decarboxylase (GAD) that binds calmodulin. In the present study, a recombinant calmodulin-binding 58-kDa petunia GAD produced in Escherichia coli was purified to homogeneity using calmodulin-affinity chromatography, and its responsiveness to calcium and calmodulin was examined in vitro. ... More
Calcium buffer injections block fucoid egg development by facilitating calcium diffusion.
AuthorsSpeksnijder JE, Miller AL, Weisenseel MH, Chen TH, Jaffe LF
JournalProc Natl Acad Sci U S A
PubMed ID2505254
'The polarity of fucoid eggs is fixed either when tip growth starts or a bit earlier. A steady flow of calcium ions into the incipient tip is thought to establish a high calcium zone that is needed for its localization and formation. To test this hypothesis, we have injected seven ... More
Fluorescence probe study of the lumenal Ca2+ of the sarcoplasmic reticulum vesicles during Ca2+ uptake and Ca2+ release.
AuthorsSaiki Y, Ikemoto N
JournalBiochem Biophys Res Commun
PubMed ID9405254
'A limited amount of information is available about the lumenal Ca2+ kinetics of the sarcoplasmic reticulum (SR). Incubation of mag-fura-2AM permitted to incorporate a sufficient amount of the probe into the SR vesicles, as determined by Mn2+ quenching. Rapid changes in the lumenal [Ca2+] ([Ca2+]lum) during Ca2+ uptake and release ... More
Calcium chelators induce association with the detergent-insoluble cytoskeleton and functional inactivation of the transferrin receptor in reticulocytes.
AuthorsMorgan EH
JournalBiochim Biophys Acta
PubMed ID2541787
'Incubation of reticulocytes with EDTA, EGTA (ethylene glycol bis(beta-aminoethyl ether)-N,N,N'',N''-tetraacetic acid) and BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N'',N''-tetraacetic acid), but not with desferrioxamine B, at temperatures above 20 degrees C resulted in the loss of their ability to take up iron in a temperature-, time- and concentration-dependent manner. No inhibition of transferrin or iron ... More
Fatty acid ethyl esters, nonoxidative metabolites of ethanol, accelerate the kinetics of activation of the human brain delayed rectifier K+ channel, Kv1.1.
AuthorsGubitosi-Klug RA, Gross RW
JournalJ Biol Chem
PubMed ID8955075
'Herein we demonstrate that the major metabolites of ethanol in neural tissues, fatty acid ethyl esters, dramatically accelerate the kinetics of the voltage-induced activation of the human brain delayed rectifier potassium channel, Kv1.1. Specifically, the external application of ethyl oleate (20 microM) to Sf9 cells expressing the recombinant Kv1.1 channel ... More
A localized elevation of cytosolic free calcium is associated with cytokinesis in the zebrafish embryo.
AuthorsChang DC, Meng C
JournalJ Cell Biol
PubMed ID8522610
'Cytokinesis, a key step in cell division, is known to be precisely regulated both in its timing and location. At present, the regulatory mechanism of cytokinesis is not well understood, although it has been suggested that calcium signaling may play an important role in this process. To test this notion, ... More
Cell-permeant Ca2+ chelators reduce early excitotoxic and ischemic neuronal injury in vitro and in vivo.
AuthorsTymianski M, Wallace MC, Spigelman I, Uno M, Carlen PL, Tator CH, Charlton MP
JournalNeuron
PubMed ID8102532
'We report the characterization of the first successful treatment of neuronal ischemic injury in vivo by cell-permeant Ca2+ chelators. The chelators attenuated glutamate-induced intracellular Ca2+ increases and neurotoxicity in neuronal explant cultures. When infused intravenously in rats, permeant fluorescent BAPTA analogs accumulated in neurons in several brain regions. BAPTA-AM, infused ... More
Estradiol reduces calcium currents in rat neostriatal neurons via a membrane receptor.
AuthorsMermelstein PG, Becker JB, Surmeier DJ
JournalJ Neurosci
PubMed ID8551343
'Until recently, steroid hormones were believed to act only on cells containing intracellular receptors. However, recent evidence suggests that steroids have specific and rapid effects at the cellular membrane. Using whole-cell patch-clamp techniques, 17 beta-estradiol was found to reduce Ba2+ entry reversibly via Ca2+ channels in acutely dissociated and cultured ... More
Kinetics of stimulus-coupled secretion in dialyzed bovine chromaffin cells in response to trains of depolarizing pulses.
AuthorsSeward EP, Nowycky MC
JournalJ Neurosci
PubMed ID8551339
'Stimulus-secretion coupling in bovine chromaffin cells was investigated with whole-cell patch-clamp recordings and capacitance detection techniques to monitor exocytosis in response to trains of depolarizing pulses. Two kinetically discrete modes of exocytotic responses were observed. In one mode, the first depolarization of a train elicited a large increase in membrane ... More
Role of calcium in mediating action of carbachol in T84 cells.
AuthorsWong SM, Lindeman RP, Parangi S, Chase HS
JournalAm J Physiol
PubMed ID2556936
'To examine the role of calcium in mediating carbachol''s action in secretory epithelia, we simultaneously measured intracellular free [Ca] [( Ca]i) and transepithelial chloride transport in T84 cells grown on collagen-coated filters. [Ca]i was measured with fura-2 and fluorescence microscopy and expressed as a relative value [( Ca]''i) normalized to ... More
Loading dependence of inositol 1,4,5-trisphosphate-induced Ca2+ release in the clonal cell line A7r5. Implications for the mechanism of quantal Ca2+ release.
AuthorsParys JB, Missiaen L, De Smedt H, Casteels R
JournalJ Biol Chem
PubMed ID8227085
'The Ca2+ content of the intracellular Ca2+ stores controls the inositol 1,4,5-trisphosphate receptor (InsP3R) in the clonal cell line A7r5. This regulation was characterized with respect to the understanding of the "quantal" release phenomenon. Independent of the loading protocol used, increasing the Ca2+ content of the stores increased the sensitivity ... More
Regulation of intracellular calcium in the mouse egg: evidence for inositol trisphosphate-induced calcium release, but not calcium-induced calcium release.
AuthorsKline JT, Kline D
JournalBiol Reprod
PubMed ID8312443
'Fertilization of the mammalian egg initiates transient and repetitive release of Ca2+ from intracellular stores. The mechanism by which these Ca2+ transients are produced is not completely known. We examined the role of two principal Ca2+ release mechanisms, inositol trisphosphate-induced Ca2+ release and Ca(2+)-induced Ca2+ release, in altering intracellular Ca2+ ... More
Chelating properties of the Ca2+ transport site of the retinal rod Na-Ca+K exchanger: evidence for a common Ca2+ and Na+ binding site.
AuthorsSchnetkamp PP
JournalBiochemistry
PubMed ID7766640
'pH-dependent Ca2+ and Na+ transport via Na-Ca+K exchange was measured in isolated and purified bovine retinal rod outer segments (ROS). Ca2+ transport was measured (1) as 45Ca uptake via reverse Na-Ca+K exchange or via Ca-Ca exchange and (2) as a Ca(2+)-induced rise in cytosolic free Ca2+ concentration via reverse Na-Ca+K ... More
The calcium current activated by T cell receptor and store depletion in human lymphocytes is absent in a primary immunodeficiency.
AuthorsPartiseti M, Le Deist F, Hivroz C, Fischer A, Korn H, Choquet D
JournalJ Biol Chem
PubMed ID7798233
'Stimulation of antigen receptors of lymphocytes triggers a transitory release of Ca2+ from internal stores and the opening of a transmembrane Ca2+ conductive pathway. The latter underlies the sustained increase of intracellular free calcium concentration, and it seems to be a key event in the Ca(2+)-dependent biochemical cascade leading to ... More
The Na+/Ca2+ exchanger NCX1 has oppositely oriented reentrant loop domains that contain conserved aspartic acids whose mutation alters its apparent Ca2+ affinity.
AuthorsIwamoto T, Uehara A, Imanaga I, Shigekawa M
JournalJ Biol Chem
PubMed ID10967097
'We examined the membrane topology and functional importance of residues in regions of the Na(+)/Ca(2+) exchanger NCX1 encompassing the conserved internal alpha repeats by substituted cysteine scanning analysis and kinetic analysis of site-directed mutants. The results suggest that both the alpha-1 repeat and a region encompassing the alpha-2 repeat and ... More
Neutrophil priming by lipopolysaccharide involves heterogeneity in calcium-mediated signal transduction. Studies using fluo-3 and flow cytometry.
AuthorsYee J, Christou NV
JournalJ Immunol
PubMed ID7679700
'Bacterial LPS is known to prime neutrophils for enhanced responses to subsequent stimulation by agonists such as FMLP. The purpose of this study was to determine whether priming is due to a uniform enhancement of function in all cells or to a recruitment of previously unresponsive neutrophils. Results from initial ... More
Potentiation of Fcepsilon receptor I-activated Ca(2+) current (I(CRAC)) by cholera toxin: possible mediation by ADP ribosylation factor.
AuthorsMcCloskey MA, Zhang L
JournalJ Cell Biol
PubMed ID10629224
'Antigen-evoked influx of extracellular Ca(2+) into mast cells may occur via store-operated Ca(2+) channels called calcium release-activated calcium (CRAC) channels. In mast cells of the rat basophilic leukemia cell line (RBL-2H3), cholera toxin (CT) potentiates antigen-driven uptake of (45)Ca(2+) through cAMP-independent means. Here, we have used perforated patch clamp recording ... More
Vasodilation by the calcium-mobilizing messenger cyclic ADP-ribose.
AuthorsBoittin FX, Dipp M, Kinnear NP, Galione A, Evans AM
JournalJ Biol Chem
PubMed ID12486132
'In artery smooth muscle, adenylyl cyclase-coupled receptors such as beta-adrenoceptors evoke Ca(2+) signals, which open Ca(2+)-activated potassium (BK(Ca)) channels in the plasma membrane. Thus, blood pressure may be lowered, in part, through vasodilation due to membrane hyperpolarization. The Ca(2+) signal is evoked via ryanodine receptors (RyRs) in sarcoplasmic reticulum proximal ... More
Induction of maturation-promoting factor during Xenopus oocyte maturation uncouples Ca(2+) store depletion from store-operated Ca(2+) entry.
AuthorsMachaca K, Haun S
JournalJ Cell Biol
PubMed ID11781335
'During oocyte maturation, eggs acquire the ability to generate specialized Ca(2+) signals in response to sperm entry. Such Ca(2+) signals are crucial for egg activation and the initiation of embryonic development. We examined the regulation during Xenopus oocyte maturation of store-operated Ca(2+) entry (SOCE), an important Ca(2+) influx pathway in ... More
Modulation of a voltage-gated calcium channel linked to activation of glutamate receptors and calcium-induced calcium release in the catfish retina.
AuthorsLinn CL, Gafka AC
JournalJ Physiol
PubMed ID11507157
'1. Catfish (Ictalurus punctatus) retinal cone horizontal cells contain an L-type calcium current that has been proposed to be involved in visual processing. Here we report on the modulation of this current by activation of glutamate receptors and calcium-induced calcium release (CICR) from intracellular calcium stores. 2. Fluorescence data obtained ... More
Dependence of hepatocytic autophagy on intracellularly sequestered calcium.
AuthorsGordon PB, Holen I, Fosse M, Røtnes JS, Seglen PO
JournalJ Biol Chem
PubMed ID8253727
'Autophagic sequestration of endogenous lactate dehydrogenase or electroinjected [3H]raffinose in isolated rat hepatocytes was strongly suppressed by the Ca2+ chelator EGTA, unless the cells had previously been electroloaded in the presence of high concentrations of Ca2+ (1.2 mM). The extracellular Ca2+ chelator bis-(o-aminophenoxy)-ethane-N,N,N'',N''-tetraacetic acid (BAPTA) and the intracellular Ca2+ chelator ... More
Angiotensin II inhibits calcium and M current channels in rat sympathetic neurons via G proteins.
AuthorsShapiro MS, Wollmuth LP, Hille B
JournalNeuron
PubMed ID7516687
'We characterized inhibition of N-type Ca2+ and M current K+ channels in rat superior cervical ganglion neurons by angiotensin II (angioII) using the patch clamp. Of 120 neurons, 97 showed inhibition of ICa (mean 32%), which was slow in onset and very slow to reverse under whole-cell recording conditions. This ... More
Multiple mechanisms of manganese-induced quenching of fura-2 fluorescence in rat mast cells.
AuthorsFasolato C, Hoth M, Penner R
JournalPflugers Arch
PubMed ID8321625
'Whole-cell patch-clamp recordings of membrane currents and fura-2 measurements of free intracellular calcium concentration ([Ca2+]i) were used to study Mn2+ influx in rat peritoneal mast cells. The calcium-selective current, activated by depletion of intracellular calcium stores (ICRAC for calcium release-activated calcium current), supports a small but measurable Mn2+ current. In ... More
Okadaic acid suppresses calcium regulation of mitosis onset in sea urchin embryos.
AuthorsPatel R, Whitaker M
JournalCell Regul
PubMed ID1654128
'We show that a phosphatase inhibitor, okadaic acid, induces premature and persistent mitosis during the first cell cycle in sea urchin embryos. Okadaic acid-induced mitosis requires protein synthesis, suggesting that it activates the protein synthesis-requiring mitotic H1 kinase. By microinjecting the calcium chelators BAPTA and EGTA and by measuring Cai ... More
Mutations in the EF-hand motif impair the inactivation of barium currents of the cardiac alpha1C channel.
AuthorsBernatchez G, Talwar D, Parent L
JournalBiophys J
PubMed ID9746514
'Calcium-dependent inactivation has been described as a negative feedback mechanism for regulating voltage-dependent calcium influx in cardiac cells. Most recent evidence points to the C-terminus of the alpha1C subunit, with its EF-hand binding motif, as being critical in this process. The EF-hand binding motif is mostly conserved between the C-termini ... More
Kinetics of the Ca(2+), H(+), and Mg(2+) interaction with the ion-binding sites of the SR Ca-ATPase.
AuthorsPeinelt C, Apell HJ
JournalBiophys J
PubMed ID11751306
'Electrochromic styryl dyes were used to investigate mutually antagonistic effects of Ca(2+) and H(+) on binding of the other ion in the E(1) and P-E(2) states of the SR Ca-ATPase. On the cytoplasmic side of the protein in the absence of Mg(2+) a strictly competitive binding sequence, H(2)E(1) <==> HE(1) ... More
Depolarization without calcium can release gamma-aminobutyric acid from a retinal neuron.
AuthorsSchwartz EA
JournalScience
PubMed ID2443977
'Calcium influx is often an essential intermediate step for the release of neurotransmitter. However, some retinal neurons appear to release transmitter by a mechanism that does not require calcium influx. It was uncertain whether depolarization released calcium from an intracellular store or released transmitter by a mechanism that does not ... More
Factors affecting the propagation of locally activated systolic Ca transients in rat ventricular myocytes.
AuthorsTrafford AW, O'Neill SC, Eisner DA
JournalPflugers Arch
PubMed ID8272377
'A method is described to activate the systolic rise of [Ca2+]i in only one region of a single, isolated cell. This is achieved by applying the calcium chelator BAPTA to the rest of the cell from a pipette. Under control conditions electrical stimulation produced a Ca transient which was uniform ... More
GABAA-mediated local synaptic pathways connect neurons in the rat suprachiasmatic nucleus.
AuthorsStrecker GJ, Wuarin JP, Dudek FE
JournalJ Neurophysiol
PubMed ID9325388
'The suprachiasmatic nucleus (SCN) in mammals functions as the biological clock controlling circadian rhythms, but the synaptic circuitry of the SCN is largely unexplored. Most SCN neurons use the neurotransmitter gamma-aminobutyric acid (GABA), and anatomic studies indicate many GABAergic synapses and local axon collaterals; however, physiological evidence for synaptic communication ... More
Cysteine-disulfide cross-linking to monitor SNARE complex assembly during endoplasmic reticulum-Golgi transport.
AuthorsFlanagan JJ, Barlowe C
JournalJ Biol Chem
PubMed ID16303754
'Assembly of cognate SNARE proteins into SNARE complexes is required for many intracellular membrane fusion reactions. However, the mechanisms that govern SNARE complex assembly and disassembly during fusion are not well understood. We have devised a new in vitro cross-linking assay to monitor SNARE complex assembly during fusion of endoplasmic ... More
Discontinuous equilibrium titrations of cooperative calcium binding to calmodulin monitored by 1-D 1H-nuclear magnetic resonance spectroscopy.
AuthorsPedigo S, Shea MA
JournalBiochemistry
PubMed ID7654722
'Calmodulin binds up to four calcium ions cooperatively in response to cellular signaling events. To understand the functional energetics of calcium activation of calmodulin, it is important to monitor individual Ca(2+)-binding sites and other positions at partial degrees of saturation. This study is the first use of 1-D proton NMR ... More
Inositol 1,4,5,6-tetrakisphosphate is phosphorylated in rat liver by a 3-kinase that is distinct from inositol 1,4,5-trisphosphate 3-kinase.
AuthorsCraxton A, Erneux C, Shears SB
JournalJ Biol Chem
PubMed ID8308002
'Liver homogenates phosphorylated inositol 1,4,5,6-tetrakisphosphate exclusively to inositol 1,3,4,5,6-pentakisphosphate. Approximately 30% of this phosphorylating activity was associated with the particulate fraction of the cell, in contrast to the inositol 3,4,5,6-tetrakisphosphate 1-kinase, which was 90% soluble. This soluble 1-kinase activity was resolved from the soluble activity that phosphorylated inositol 1,4,5,6-tetrakisphosphate by ... More
The physiologic concentration of inositol 1,4,5-trisphosphate in the oocytes of Xenopus laevis.
'To measure the concentration of inositol 1,4,5-trisphosphate ([IP3]) in small regions of single Xenopus oocytes, a biological detector cell was combined with capillary electrophoresis. This method is 10, 000 times more sensitive than all existing assays enabling subcellular measurement of [IP3] in Xenopus oocytes. Upon addition of lysophosphatidic acid to ... More
A G protein gamma subunit-specific peptide inhibits muscarinic receptor signaling.
AuthorsAzpiazu I, Cruzblanca H, Li P, Linder M, Zhuo M, Gautam N
JournalJ Biol Chem
PubMed ID10585394
'Muscarinic acetylcholine receptors modulate the function of a variety of effectors through heterotrimeric G proteins. A prenylated peptide specific to the G protein gamma5 subunit type inhibits G protein activation by the M2 muscarinic receptor in a reconstitution assay. Scrambling the amino acid sequence of the peptide significantly reduces the ... More
Intracellular injection of Ca2+ chelators blocks induction of long-term depression in rat visual cortex.
AuthorsBröcher S, Artola A, Singer W
JournalProc Natl Acad Sci U S A
PubMed ID1309603
'In a variety of brain structures repetitive activation of synaptic connections can lead to long-term potentiation (LTP) or long-term depression (LTD) of synaptic transmission, and these modifications are held responsible for memory formation. Here we examine the role of postsynaptic Ca2+ concentration in the induction of LTD in the neocortex. ... More
Halothane inhibits two components of calcium current in clonal (GH3) pituitary cells.
AuthorsHerrington J, Stern RC, Evers AS, Lingle CJ
JournalJ Neurosci
PubMed ID1648606
'The effect of halothane on isolated calcium (Ca2+) current of clonal (GH3) pituitary cells was investigated using standard whole-cell clamp techniques at room temperature. Halothane (0.1-5.0 mM) reversibly reduced both the low-threshold, transient [low-voltage-activated (LVA)] component and the high-threshold [high-voltage-activated (HVA)] component of Ca2+ current. Halothane had little effect on ... More
Induction of two K+ currents by complement component C5a in mouse macrophages.
AuthorsIchinose M, Hara N, Sawada M, Maeno T
JournalBiochim Biophys Acta
PubMed ID1384705
'Puff application of complement component C5a (5 x 10(-8) M) onto peritoneal macrophages from thioglycollate-stimulated mice induced two kinds of outward current at a holding potential of -68 mV, a slowly-rising sustained outward current and a spike-like transient outward current. Quinidine (2 x 10(-4) M) and tetraethylammonium (10(-2) M) partially ... More
Quantal transmitter secretion from myocytes loaded with acetylcholine.
AuthorsDan Y, Poo MM
JournalNature
PubMed ID1436036
'It is well known that transmitter secretion requires specialized secretory organelles, the synaptic vesicles, for the packaging, storage and exocytotic release of the transmitter. Here we report that when acetylcholine (ACh) is loaded into an isolated Xenopus myocyte, there is spontaneous quantal release of ACh from the myocyte which results ... More
A theoretical study of calcium microdomains in turtle hair cells.
AuthorsWu YC, Tucker T, Fettiplace R
JournalBiophys J
PubMed ID8913569
'Confocal imaging has revealed microdomains of intracellular free Ca2+ in turtle hair cells evoked by depolarizing pulses and has delineated factors affecting the growth and dissipation of such domains. However, imaging experiments have limited spatial and temporal resolution. To extend the range of the results we have developed a three-dimensional ... More
Reconstitution of the skeletal muscle ryanodine receptor-Ca2+ release channel protein complex into proteoliposomes.
AuthorsLee HB, Xu L, Meissner G
JournalJ Biol Chem
PubMed ID8175760
'The 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid-solubilized 30 S ryanodine receptor (RyR)/Ca2+ release channel complex from rabbit skeletal muscles, purified by density gradient centrifugation, was reconstituted with an excess of phospholipid into proteoliposomes by removal of the detergent by dialysis. Reconstituted proteoliposomes were concentrated by centrifugation, frozen and thawed, and sonicated. [3H]Ryanodine binding measurements ... More
Ras-dependent mitogen-activated protein kinase activation by G protein-coupled receptors. Convergence of Gi- and Gq-mediated pathways on calcium/calmodulin, Pyk2, and Src kinase.
AuthorsDella Rocca GJ, van Biesen T, Daaka Y, Luttrell DK, Luttrell LM, Lefkowitz RJ
JournalJ Biol Chem
PubMed ID9235901
'Many receptors that couple to heterotrimeric guanine-nucleotide binding proteins (G proteins) have been shown to mediate rapid activation of the mitogen-activated protein kinases Erk1 and Erk2. In different cell types, the signaling pathways employed appear to be a function of the available repertoire of receptors, G proteins, and effectors. In ... More
Activation of a voltage-dependent chloride current in human neutrophils by phorbol 12-myristate 13-acetate and formyl-methionyl-leucyl-phenylalanine. The role of protein kinase C.
AuthorsSchumann MA, Raffin TA
JournalJ Biol Chem
PubMed ID8300564
'Calcium-activated, voltage-independent Cl- currents have been demonstrated in human neutrophils (Krause, K.-H., and Welsh, M.J. (1990) J. Clin. Invest. 85, 491-498). The activation is mediated by calcium/calmodulin-dependent protein kinase and not by protein kinase C (PKC) (Schumann, M., Gardner, A.P., and Raffin, T.A. (1993) J. Biol. Chem. 268, 2134-2140). It ... More
A specific point mutant at position 1 of the influenza hemagglutinin fusion peptide displays a hemifusion phenotype.
AuthorsQiao H, Armstrong RT, Melikyan GB, Cohen FS, White JM
JournalMol Biol Cell
PubMed ID10436026
'We showed previously that substitution of the first residue of the influenza hemagglutinin (HA) fusion peptide Gly1 with Glu abolishes fusion activity. In the present study we asked whether this striking phenotype was due to the charge or side-chain volume of the substituted Glu. To do this we generated and ... More
Assessment of intra-SR free [Ca] and buffering in rat heart.
AuthorsShannon TR, Bers DM
JournalBiophys J
PubMed ID9284319
'To measure the free intrasarcoplasmic reticulum [Ca] ([Ca]SR) in isolated rat cardiac microsomes, ventricular tissue was homogenized in the presence of the low-affinity Ca indicator furaptra. Stepwise increases in cuvette [Ca] ([Ca]c) in the presence of ATP caused progressive increases in steady-state intravesicular fluorescence ratio to a maximum (Rmax). Steady-state ... More
Permeation and gating properties of the novel epithelial Ca(2+) channel.
'The recently cloned epithelial Ca(2+) channel (ECaC) constitutes the Ca(2+) influx pathway in 1,25-dihydroxyvitamin D(3)-responsive epithelia. We have combined patch-clamp analysis and fura-2 fluorescence microscopy to functionally characterize ECaC heterologously expressed in HEK293 cells. The intracellular Ca(2+) concentration in ECaC-expressing cells was closely correlated with the applied electrochemical Ca(2+) gradient, ... More
Calcium-dependent enhancement of calcium current in smooth muscle by calmodulin-dependent protein kinase II.
'Calcium entry through voltage-activated Ca2+ channels is important in regulating many cellular functions. Activation of these channels in many cell types results in feedback regulation of channel activity. Mechanisms linking Ca2+ channel activity with its downregulation have been described, but little is known of the events responsible for the enhancement ... More
Cyclic ADP-ribose-gated Ca2+ release in sea urchin eggs requires an elevated.
AuthorsGuo X, Becker PL
JournalJ Biol Chem
PubMed ID9202011
'Cyclic ADP-ribose (cADPr) has been shown to release intracellular Ca2+ from sea urchin eggs and a variety of vertebrate cell types, although its mechanism of action remains elusive. We employed the caged version of cADPr to study the [Ca2+] transient kinetics in intact sea urchin eggs for insights into how ... More
Binding of divalent cation and nucleotide to G-actin in the presence of profilin.
AuthorsPerelroizen I, Carlier MF, Pantaloni D
JournalJ Biol Chem
PubMed ID7829477
'The effect of profilin, a G-actin binding protein, on the mechanism of exchange of the tightly bound metal ion and nucleotide on G-actin, has been investigated. 1) In low ionic strength buffer, profilin increases the rates of Ca2+ and Mg2+ dissociation from G-actin 250- and 50-fold, respectively. On the profilin-actin ... More
Precisely localized LTD in the neocortex revealed by infrared-guided laser stimulation.
AuthorsDodt H, Eder M, Frick A, Zieglgänsberger W
JournalScience
PubMed ID10506556
'In a direct approach to elucidate the origin of long-term depression (LTD), glutamate was applied onto dendrites of neurons in rat neocortical slices. An infrared-guided laser stimulation was used to release glutamate from caged glutamate in the focal spot of an ultraviolet laser. A burst of light flashes caused an ... More
Fluorescent calcium indicators: subcellular behavior and use in confocal imaging.
AuthorsO'Malley DM, Burbach BJ, Adams PR
JournalMethods Mol Biol
PubMed ID10231797
Fluorescence imaging of Na+ influx via P2X receptors in cochlear hair cells.
AuthorsHousley GD, Raybould NP, Thorne PR
JournalHear Res
PubMed ID9641314
'The adenosine 5''-triphosphate (ATP)-activated membrane conductance, mediated by P2X receptors, was examined in isolated guinea-pig cochlear inner and outer hair cells. Photo-activated release of caged-ATP elicted a 30-ms latency inwardly rectifying non-selective cation conductance, blocked by the P2X receptor antagonist pyridoxalphosphate-6-azophenyl-2'',4''-disulphonic acid (PPADS; 10-100 microM), consistent with the direct activation ... More
Calcium and the mechanism of light adaptation in vertebrate photoreceptors.
AuthorsFain GL, Matthews HR
JournalTrends Neurosci
PubMed ID1699328
'Vertebrate photoreceptors transduce the absorption of light into a hyperpolarizing change in membrane potential. The mechanism of transduction is becoming fairly well understood and has been shown to occur via a G protein-coupled decrease in cyclic GMP. Attention is now turning to the way the enzymatic machinery in the outer ... More