Cadherins mediate intercellular mechanical signaling in fibroblasts by activation of stretch-sensitive calcium-permeable channels.
AuthorsKo KS, Arora PD, McCulloch CA
JournalJ Biol Chem
PubMed ID11466312
'Cells in mechanically active environments form extensive, cadherin-mediated intercellular junctions that are important in tissue remodeling and differentiation. Currently, it is unknown whether adherens junctions in connective tissue fibroblasts transmit mechanical signals and coordinate multicellular adaptations to physical forces. We hypothesized that cadherins mediate intercellular mechanotransduction by activating calcium-permeable, stretch-sensitive ... More
Calbindin-D28K, a 1 alpha,25-dihydroxyvitamin D3-induced calcium-binding protein, binds five or six Ca2+ ions with high affinity.
AuthorsLeathers VL, Linse S, Forsén S, Norman AW
JournalJ Biol Chem
PubMed ID2351677
'Calbindin-D28K is a 1 alpha,25-dihydroxyvitamin D3-dependent protein that belongs to the superfamily of high affinity calcium-binding proteins which includes parvalbumin, calmodulin, and troponin C. All of these proteins bind Ca2+ ligands by an alpha-helix-loop-alpha-helix domain that is termed an EF-hand. Calbindin-D28K has been reported previously to have four high affinity ... More
Reducing inositol lipid hydrolysis, Ins(1,4,5)P3 receptor availability, or Ca2+ gradients lengthens the duration of the cell cycle in Xenopus laevis blastomeres.
AuthorsHan JK, Fukami K, Nuccitelli R
JournalJ Cell Biol
PubMed ID1309810
'We have microinjected a mAb specifically directed to phosphatidylinositol 4,5-bisphosphate (PIP2) into one blastomere of two-cell stage Xenopus laevis embryos. This antibody binds to endogenous PIP2 and reduces its rate of hydrolysis by phospholipase C. Antibody-injected blastomeres undergo partial or complete arrest of the cell cycle whereas the uninjected sister ... More
Effects of the amino-terminal regions of tropomyosin and troponin T on thin filament assembly.
AuthorsWilladsen KA, Butters CA, Hill LE, Tobacman LS
JournalJ Biol Chem
PubMed ID1429713
'Bacterially expressed alpha-tropomyosin lacks the amino-terminal acetylation present in muscle tropomyosin and binds poorly to actin (Hitchcock-DeGregori, S. E., and Heald, R. W. (1987) J. Biol. Chem. 262, 9730-9735). Using a linear lattice model, we determined the affinity (Ko) of unacetylated tropomyosin or troponin-unacetylated tropomyosin for an isolated site on ... More
The sperm-induced Ca2+ wave following fertilization of the Xenopus egg requires the production of Ins(1, 4, 5)P3.
AuthorsNuccitelli R, Yim DL, Smart T
JournalDev Biol
PubMed ID7687224
'We used fluorescence ratio imaging of fura-2 in the egg of Xenopus laevis to study the initiation and propagation of the wave of increased free Ca2+ that is normally triggered at fertilization. Naturally matured, jellied eggs were injected with fura-2 and ratio-imaged with fluorescence excitation at 350 and 385 nm ... 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
Secretory responses of rat peritoneal mast cells to high intracellular calcium.
AuthorsPenner R, Neher E
JournalFEBS Lett
PubMed ID3123272
'The patch-clamp technique was used to investigate the secretory responses of rat peritoneal mast cells at various intracellular calcium concentrations ([Ca2+]i). When Calcium was introduced into the cell with pipette-loaded dibromo-BAPTA, elevation of [Ca2+]i into the range 1-10 microM induced membrane capacitance increases indicative of exocytosis in a concentration-dependent manner. ... More
Sphingomyelinase induces lipid microdomain formation in a fluid phosphatidylcholine/sphingomyelin membrane.
AuthorsHolopainen JM, Subramanian M, Kinnunen PK
JournalBiochemistry
PubMed ID9860872
'The behaviors of two chemically well-defined sphingolipids, N-palmitoyl-sphingomyelin (C16:0-SM) and the corresponding ceramide (C16:0-Cer), in a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) matrix were compared. Minor attenuation of lateral diffusion upon increasing the mole fraction of C16:0-SM (XSM, up to 0.25) was indicated by the slight decrement in the excimer/monomer intensity ratio (Ie/Im) for ... 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
Free calcium in Micrasterias: local gradients are not detected in growing lobes.
AuthorsHolzinger A, Callaham DA, Hepler PK, Meindl U
JournalEur J Cell Biol
PubMed ID8521876
'Intracellular free Ca2+ ([Ca2+]) has been measured in growing unicells of two species of the green alga, Micrasterias, which have been injected with the indicator dye fura-2-dextran. Ratiometric imaging of Micrasterias denticulata yields levels of 170 to 200 nM [Ca2+] but fails to reveal a significant [Ca2+] gradient associated with ... More
Identification of Mg2+-binding sites and the role of Mg2+ on target recognition by calmodulin.
AuthorsOhki S, Ikura M, Zhang M
JournalBiochemistry
PubMed ID9100027
'The binding of Mg2+ to calmodulin (CaM) and the effect of Mg2+ on the binding of Ca2+-CaM to target peptides were examined using two-dimensional nuclear magnetic resonance and fluorescence spectroscopic techniques. We found that Mg2+ preferentially binds to Ca2+-binding sites I and IV of CaM in the absence of Ca2+ ... More
Na+-Ca2+ exchanger remodeling in pressure overload cardiac hypertrophy.
AuthorsWang Z, Nolan B, Kutschke W, Hill JA
JournalJ Biol Chem
PubMed ID11279089
'Perturbations of Ca(2+) metabolism are central to the pathogenesis of cardiac hypertrophy. The electrogenic Na(+)-Ca(2+) exchanger mediates a substantial component of transmembrane Ca(2+) movement in cardiac myocytes and is up-regulated in heart failure. However, the role of the exchanger in the pathogenesis of cardiac hypertrophy is poorly understood. Thoracic aortic ... More
Electrostatic contributions to the binding of Ca2+ in calbindin D9k.
AuthorsLinse S, Johansson C, Brodin P, Grundström T, Drakenberg T, Forsén S
JournalBiochemistry
PubMed ID1988017
'A set of accurate experimental data is provided for Ca2+ ion binding to calbindin D9k, a protein in the calmodulin superfamily of intracellular regulatory proteins. The study comprises both the role of protein surface charges and the effects of added electrolyte. The two macroscopic Ca2(+)-binding constants K1 and K2 are ... More
Mutations in actin subdomain 3 that impair thin filament regulation by troponin and tropomyosin.
AuthorsKorman VL, Tobacman LS
JournalJ Biol Chem
PubMed ID10428784
'Thin filament-mediated regulation of striated muscle contraction involves conformational switching among a few quaternary structures, with transitions induced by binding of Ca(2+) and myosin. We establish and exploit Saccharomyces cerevisiae actin as a model system to investigate this process. Ca(2+)-sensitive troponin-tropomyosin binding affinities for wild type yeast actin are seen ... More
Drug binding to cardiac troponin C.
AuthorsKleerekoper Q, Putkey JA
JournalJ Biol Chem
PubMed ID10446160
'Compounds that sensitize cardiac muscle to Ca(2+) by intervening at the level of regulatory thin filament proteins would have potential therapeutic benefit in the treatment of myocardial infarctions. Two putative Ca(2+) sensitizers, EMD 57033 and levosimendan, are reported to bind to cardiac troponin C (cTnC). In this study, we use ... More
Ca2+ released via IP3 receptors is required for furrow deepening during cytokinesis in zebrafish embryos.
AuthorsLee KW, Webb SE, Miller AL
JournalInt J Dev Biol
PubMed ID14584779
'We have previously visualized three Ca2+ transients, generated by release from intracellular stores, which are associated with cytokinesis during the early cell division cycles of zebrafish embryos: the furrow positioning, propagation and deepening transients. Here we demonstrate the requirement of the latter for furrow deepening, and identify the Ca2+ release ... More
Calcium mobilization is required for nuclear vesicle fusion in vitro: implications for membrane traffic and IP3 receptor function.
AuthorsSullivan KM, Busa WB, Wilson KL
JournalCell
PubMed ID8391933
'We studied the fusion of nuclear vesicles bound to chromatin in Xenopus egg extracts. Fusion was inhibited by 5 mM BAPTA, a Ca2+ buffer that suppresses cytosolic [Ca2+] gradients. The BAPTA-inhibited step in fusion was biochemically distinct from, and occurred later than, the GTP gamma S-sensitive step mediated by the ... More
Effects of cytoplasmic and luminal pH on Ca(2+) release channels from rabbit skeletal muscle.
AuthorsLaver DR, Eager KR, Taoube L, Lamb GD
JournalBiophys J
PubMed ID10733964
'Ryanodine receptor (RyR)-Ca(2+) release channels from rabbit skeletal muscle were incorporated into lipid bilayers. The effects of cytoplasmic and luminal pH were studied separately over the pH range 5-8, using half-unit intervals. RyR activity (at constant luminal pH of 7.5) was inhibited at acidic cytoplasmic pH, with a half-inhibitory pH ... More
Effects of intracellular calcium chelation on voltage-dependent and calcium-dependent currents in cat neocortical neurons.
AuthorsSchwindt PC, Spain WJ, Crill WE
JournalNeuroscience
PubMed ID1316566
'Large neurons from layer V in a slice preparation of cat sensorimotor cortex were impaled with microelectrodes containing KCl plus different concentrations of the Ca2+ chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N'',N''-tetra-acetic acid (BAPTA) or two of its derivatives. Impalement with electrodes containing high BAPTA (200 mM) quickly abolished Ca(2+)-dependent afterhyperpolarizations. Spike parameters were normal, ... More
The effect of temperature and ionic strength on the apparent Ca-affinity of EGTA and the analogous Ca-chelators BAPTA and dibromo-BAPTA.
AuthorsHarrison SM, Bers DM
JournalBiochim Biophys Acta
PubMed ID3113491
'The apparent calcium association constants (K''Ca) of ethylene glycol bis(beta-aminoethyl ether)-N,N,N'',N''-tetraacetic acid (EGTA), 1,2-bis(o-aminophenoxy)ethane-N,N,N'',N''-tetraacetic acid (BAPTA) and 1,2-bis 2-bis(o-amino-5-bromophenoxy)ethane-N,N,N'',N''-tetraacetic acid (dibromo-BAPTA) were measured using the method described by Bers (Am. J. Physiol. 242 (1982) C404-408). The purity of the three ligands determined from the chi-intercept of Scatchard plots were 96.3%, ... More
Reduced capacitative calcium entry correlates with vesicle accumulation and apoptosis.
'A preneoplastic variant of Syrian hamster embryo cells, sup(+), exhibits decreased endoplasmic reticulum calcium levels and subsequently undergoes apoptosis in low serum conditions (Preston, G. A., Barrett, J. C., Biermann, J. A., and Murphy, E. (1997) Cancer Res. 57, 537-542). This decrease in endoplasmic reticulum calcium appears to be due, ... More
Calcium pools in saponin-permeabilized guinea pig hepatocytes.
AuthorsBurgess GM, McKinney JS, Fabiato A, Leslie BA, Putney JW
JournalJ Biol Chem
PubMed ID6654915
'The plasma membranes of isolated guinea pig hepatocytes were made permeable with saponin. The cells were then suspended in a medium resembling cytosol in which the level of ATP was kept constant with an ATP-regenerating system. Intracellular ATP-dependent 45Ca and 40Ca sequestration was then followed at various concentrations of Ca2+ ... More
On the dissociation constants of BAPTA-type calcium buffers.
AuthorsPethig R, Kuhn M, Payne R, Adler E, Chen TH, Jaffe LF
JournalCell Calcium
PubMed ID2515001
'We have determined or redetermined the calcium dissociation constants of seven BAPTA-type buffers with KD''s in the range from 0.4 microM to about 20 mM in 300 mM KCl. These include four newly synthesized ones: 5-nitro BAPTA; 5,5''-dinitro BAPTA; 5-methyl-5''-nitro BAPTA; and 5-methyl-5''-formyl BAPTA. Moreover, we tabulate dissociation constants or ... More
Intracellular measurements of ion activities.
AuthorsTsien RY
JournalAnnu Rev Biophys Bioeng
PubMed ID6347046
A practical guide to the preparation of Ca2+ buffers.
AuthorsBers DM, Patton CW, Nuccitelli R
JournalMethods Cell Biol
PubMed ID8201981
Ca2+ is an obligatory intermediate in the excitation cascade of limulus photoreceptors.
AuthorsShin J, Richard EA, Lisman JE
JournalNeuron
PubMed ID8240808
We have investigated the role of Ca2+ in the excitation of Limulus photoreceptors by intracellular injection of the Ca2+ buffer, 5,5'-dibromo-BAPTA. Buffer with free Ca2+ of 0.5 or 5 microM slowed the rising edge of the light response over 100-fold and greatly reduced both the transient and plateau phases of ... More
Intracellular Ca2+ buffers disrupt muscarinic suppression of Ca2+ current and M current in rat sympathetic neurons.
AuthorsBeech DJ, Bernheim L, Mathie A, Hille B
JournalProc Natl Acad Sci U S A
PubMed ID1846449
The role of intracellular Ca2+ concentration ([Ca2+]i) in the muscarinic suppression of Ca2+ current and M-type K+ current has been investigated in isolated rat sympathetic neurons using the whole-cell patch-clamp technique and fura-2 fluorescence measurements. Muscarinic stimulation suppressed currents without raising [Ca2+]i. Nonetheless, intracellular bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetate (BAPTA) (11-12 mM), a Ca2+ ... More
Detection of phase separation in fluid phosphatidylserine/phosphatidylcholine mixtures.
AuthorsHinderliter AK, Huang J, Feigenson GW
JournalBiophys J
PubMed ID7858127
The nonideal mixing of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoserine, (16:0, 18:1)PS, and 1,2-didodecenoyl-sn-glycero-3-phosphocholine, (12:1, 12:1)PC, in fluid lamellar model membranes was studied by measuring binding of aqueous Ca2+ ions and by x-ray diffraction. A region of two-phase coexistence was found by invariance of the aqueous concentration and by the appearance of two sets of ... More
The role of calcium in cell division.
AuthorsHepler PK
JournalCell Calcium
PubMed ID7820852
Calcium ions (Ca2+) appear to participate in the regulation of several aspects of cell division. Evidence is accumulating that transients or local gradients in the [Ca2+] contribute to different events including nuclear envelope breakdown and reformation, cleavage furrow formation and growth, and cell plate formation. At present there is little ... More
Calcium ion binding between lipid bilayers: the four-component system of phosphatidylserine, phosphatidylcholine, calcium chloride, and water.
AuthorsFeigenson GW
JournalBiochemistry
PubMed ID2540823
Ca2+ binding between lamellae of phosphatidylserine (PS) and phosphatidylcholine (PC) gives rise to a rigid phase of Ca(PS)2. When aqueous Ca2+, hydrated PS/PC, and Ca(PS)2 coexist at equilibrium, the aqueous Ca2+ concentration is invariant and is characteristic of the PS/PC ratio. This characteristic Ca2+ concentration is 0.040 microM for palmitoyloleoylphosphatidylserine ... More
Noise analysis of ion channels in non-space-clamped cables: estimates of channel parameters in olfactory cilia.
AuthorsLarsson HP, Kleene SJ, Lecar H
JournalBiophys J
PubMed ID9138566
Ion channels in the cilia of olfactory neurons are part of the transduction machinery of olfaction. Odorant stimuli have been shown to induce a biphasic current response, consisting of a cAMP-activated current and a Ca(2+)-activated Cl- current. We have developed a noise analysis method to study ion channels in leaky ... More
Calbindin D(9k): a protein optimized for calcium binding at neutral pH.
AuthorsKesvatera T, Jönsson B, Telling A, Tõugu V, Vija H, Thulin E, Linse S
JournalBiochemistry
PubMed ID11735416
The binding of calcium ions by EF-hand proteins depends strongly on the electrostatic interactions between Ca(2+) ions and negatively charged residues of these proteins. We have investigated the pH dependence of the binding of Ca(2+) ions by calbindin D(9k). This protein offers a unique possibility for interpretation of such data ... More
Rhodopsin kinase inhibition by recoverin. Function of recoverin myristoylation.
AuthorsCalvert PD, Klenchin VA, Bownds MD
JournalJ Biol Chem
PubMed ID7592614
Recoverin is a Ca(2+)-binding protein that may play a role in vertebrate photoreceptor light adaptation by imparting Ca2+ sensitivity to rhodopsin kinase. It is heterogeneously acylated (mostly myristoylated) at its amino-terminal glycine. Recent studies have shown that recoverin myristolyation is necessary for its Ca(2+)-dependent membrane association and cooperative Ca2+ binding. ... More
Persistence of the interaction of calmodulin with adenylyl cyclase: implications for integration of transient calcium stimuli.
AuthorsOnyike CU, Lin AH, Abrams TW
JournalJ Neurochem
PubMed ID9721756
Ca2+/calmodulin-sensitive adenylyl cyclase plays a role in several forms of synaptic plasticity and learning. To understand how cellular signals from neuronal activity during behavioral stimuli might be integrated by adenylyl cyclase, we have characterized the response of type I adenylyl cyclase to transient Ca2+ stimuli. Stimulation by a several second ... More
Detection in living cells of Ca2+-dependent changes in the fluorescence emission of an indicator composed of two green fluorescent protein variants linked by a calmodulin-binding sequence. A new class of fluorescent indicators.
AuthorsRomoser VA, Hinkle PM, Persechini A
JournalJ Biol Chem
PubMed ID9148946
We have designed a novel fluorescent indicator composed of two green fluorescent protein variants joined by the calmodulin-binding domain from smooth muscle myosin light chain kinase. When (Ca2+)4-calmodulin is bound to the indicator (Kd = 0.4 nM), fluorescence resonance energy transfer between the two fluorophores is attenuated; the ratio of ... More
Localized calcium signals along the cleavage furrow of the Xenopus egg are not involved in cytokinesis.
AuthorsNoguchi T, Mabuchi I
JournalMol Biol Cell
PubMed ID11950937
It has been proposed that a localized calcium (Ca) signal at the growing end of the cleavage furrow triggers cleavage furrow formation in large eggs. We have examined the possible role of a Ca signal in cleavage furrow formation in the Xenopus laevis egg during the first cleavage. We were ... More
TPEN, a Zn2+/Fe2+ chelator with low affinity for Ca2+, inhibits lamin assembly, destabilizes nuclear architecture and may independently protect nuclei from apoptosis in vitro.
AuthorsShumaker DK, Vann LR, Goldberg MW, Allen TD, Wilson KL
JournalCell Calcium
PubMed ID9601611
We used Xenopus egg extracts to examine the effects of TPEN, a chelator with strong affinities for Zn2+, Fe2+, and Mn2+, on nuclear assembly in vitro. At concentrations above 1 mM, TPEN blocked the assembly of the nuclear lamina and produced nuclei that were profoundly sensitive to stress-induced balloon-like 'shedding' ... More
Simultaneous measurement of Ca2+, contraction, and potential in cardiac myocytes.
AuthorsSpurgeon HA, Stern MD, Baartz G, Raffaeli S, Hansford RG, Talo A, Lakatta EG, Capogrossi MC
JournalAm J Physiol
PubMed ID2309919
A system is described that can simultaneously record cytosolic Ca2+ concentration ([Ca2+]i), cell length, and either membrane potential or current in single cardiac myocytes loaded with the fluorescent Ca2+ indicator indo-1. Fluorescence is excited by epi-illumination with 3.8-microsecond flashes of 350 +/- 5 nm light from a xenon arc. Indo-1 ... More
Mutational effects on the cooperativity of Ca2+ binding in calmodulin.
AuthorsWaltersson Y, Linse S, Brodin P, Grundström T
JournalBiochemistry
PubMed ID8347591
The importance of the aspartate ligand in the +Y Ca2+ coordinating position of two EF-hands of calmodulin has been investigated. Synthetic calmodulin genes were used to produce engineered proteins with the wild-type bovine sequence as well as with aspartate 58 in Ca(2+)-binding site II and/or aspartate 95 in site III ... More
A transient rise in cytoplasmic free calcium is required to induce cytokinesis in zoosporangia of Phytophthora cinnamomi.
AuthorsJackson SL, Hardham AR
JournalEur J Cell Biol
PubMed ID8907619
We studied the role of cytoplasmic free Ca2+ concentration ([Ca2+]i) in cytokinesis of zoosporangia of the water mold Phytophthora cinnamomi. In these cells cytokinesis is separated from nuclear division and can be triggered at precisely determined times by cold shock. Changes in [Ca2+]i were monitored by ratiometric fluorescence imaging of ... More
ATP regulation of type 1 inositol 1,4,5-trisphosphate receptor channel gating by allosteric tuning of Ca(2+) activation.
AuthorsMak DO, McBride S, Foskett JK
JournalJ Biol Chem
PubMed ID10428789
Inositol 1,4,5-trisphosphate (InsP(3)) mobilizes intracellular Ca(2+) by binding to its receptor (InsP(3)R), an endoplasmic reticulum-localized Ca(2+) release channel. Patch clamp electrophysiology of Xenopus oocyte nuclei was used to study the effects of cytoplasmic ATP concentration on the cytoplasmic Ca(2+) ([Ca(2+)](i)) dependence of single type 1 InsP(3)R channels in native endoplasmic ... More
Calcium-dependent binding of recoverin to membranes monitored by surface plasmon resonance spectroscopy in real time.
AuthorsLange C, Koch KW
JournalBiochemistry
PubMed ID9315839
Recoverin is an N-myristoylated Ca2+-binding protein that serves as a Ca2+-sensor in visual transduction. We studied the dynamics of its Ca2+-dependent membrane association which depends on the myristoyl modification (Ca2+-myristoyl switch) by surface plasmon resonance spectroscopy. Either recoverin or phospholipid vesicles were immobilized on a sensor chip surface, and the ... More
ATP can stimulate exocytosis in rat brown adipocytes without apparent increases in cytosolic Ca2+ or G protein activation.
AuthorsLee SC, Pappone PA
JournalBiophys J
PubMed ID10096924
Extracellular ATP activates large increases in cell surface area and membrane turnover in rat brown adipocytes (Pappone, P. A., and Lee, S. C. 1996. J. Gen. Physiol. 108:393-404). We used whole-cell patch clamp membrane capacitance measurements of membrane surface area concurrently with fura-2 ratio imaging of intracellular calcium to test ... More
Cooperative effect of calcium binding to adjacent troponin molecules on the thin filament-myosin subfragment 1 MgATPase rate.
AuthorsButters CA, Tobacman JB, Tobacman LS
JournalJ Biol Chem
PubMed ID9148936
The myosin subfragment 1 (S1) MgATPase rate was measured using thin filaments with known extents of Ca2+ binding controlled by varying the ratio of native cardiac troponin versus an inhibitory troponin with a mutation in the sole regulatory Ca2+ binding site of troponin C. Fractional MgATPase activation was less than ... More
Spatial calcium buffering in saccular hair cells.
AuthorsRoberts WM
JournalNature
PubMed ID8479539
The potential importance of intracellular calcium-binding proteins in rapid and highly localized Ca2+ signalling is poorly understood. During fast synaptic transmission, which occurs at specialized active zones where Ca2+ diffuses only a few tens of nanometers from channels to neurotransmitter release sites, a cytoplasmic Ca2+ buffer would have to be ... More
Functional consequences of troponin T mutations found in hypertrophic cardiomyopathy.
AuthorsTobacman LS, Lin D, Butters C, Landis C, Back N, Pavlov D, Homsher E
JournalJ Biol Chem
PubMed ID10497196
Missense mutations in the cardiac thin filament protein troponin T (TnT) are a cause of familial hypertrophic cardiomyopathy (FHC). To understand how these mutations produce dysfunction, five TnTs were produced and purified containing FHC mutations found in several regions of TnT. Functional defects were diverse. Mutations F110I, E244D, and COOH-terminal ... More
New calcium indicators and buffers with high selectivity against magnesium and protons: design, synthesis, and properties of prototype structures.
AuthorsTsien RY
JournalBiochemistry
PubMed ID6770893
A new family of high-affinity buffers and optical indicators for Ca2+ is rationally designed and synthesized. The parent compound is 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), a relative of the well-known chelator EGTA [ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] in which methylene links between oxygen and nitrogen are replaced by benzene rings. BAPTA and ... More
The NO pathway acts late during the fertilization response in sea urchin eggs.
AuthorsLeckie C, Empson R, Becchetti A, Thomas J, Galione A, Whitaker M
JournalJ Biol Chem
PubMed ID12540836
Both the inositol 1,4,5-trisphosphate (InsP(3)) and ryanodine receptor pathways contribute to the Ca(2+) transient at fertilization in sea urchin eggs. To date, the precise contribution of each pathway has been difficult to ascertain. Evidence has accumulated to suggest that the InsP(3) receptor pathway has a primary role in causing Ca(2+) ... More
A calbindin D9k mutant with reduced calcium affinity and enhanced cooperativity. Metal ion binding, stability, and structural studies.
AuthorsLinse S, Bylsma NR, Drakenberg T, Sellers P, Forsén S, Thulin E, Svensson LA, Zajtzeva I, Zajtsev V, Marek J
JournalBiochemistry
PubMed ID7918470
In the native calcium-binding protein calbindin D9k (M(r) 8.700; 75aa; 2 EF-hands), the backbone carbonyl oxygen of Glu60 coordinates the Ca2+ ion in the C-terminal site (site II). The carboxylate group of the same residue forms a hydrogen bond to a water molecule that constitutes a Ca2+ ligand in the ... More
Ca(2+)-dependent interaction of recoverin with rhodopsin kinase.
AuthorsChen CK, Inglese J, Lefkowitz RJ, Hurley JB
JournalJ Biol Chem
PubMed ID7629115
Recoverin (Rv) is a myristoylated Ca(2+)-binding protein present primarily in bovine photoreceptors. It represents a newly identified family of neuronal specific Ca(2+)-binding proteins that includes neurocalcin, hippocalcin, and guanylyl cyclase-activating protein. To investigate the function of Rv in photoreceptors, we identified proteins that bind immobilized Rv in a Ca(2+)-dependent manner. ... More
Pollen tube growth is coupled to the extracellular calcium ion flux and the intracellular calcium gradient: effect of BAPTA-type buffers and hypertonic media.
AuthorsPierson ES, Miller DD, Callaham DA, Shipley AM, Rivers BA, Cresti M, Hepler PK
JournalPlant Cell
PubMed ID7866026
Lily pollen tubes possess a steep, tip-focused intracellular Ca2+ gradient and a tip-directed extracellular Ca2+ influx. Ratiometric ion imaging revealed that the gradient extends from above 3.0 microM at the apex to approximately 0.2 microM within 20 microns from the tip, while application of the Ca(2+)-specific vibrating electrode indicated that ... More
Calcium buffer injections inhibit cytokinesis in Xenopus eggs.
A slow cortical wave of high calcium accompanies the elongation of cleavage furrows in medaka fish eggs as well as in Xenopus eggs. We explored the role of such waves by injecting calcium buffers into Xenopus eggs at various times before and during first and second cleavage. Injection earlier than ... More
Detection of coexisting fluid phospholipid phases by equilibrium Ca2+ binding: peptide-poor L alpha and peptide-rich HII phase coexistence in gramicidin A'/phospholipid dispersions.
AuthorsDibble AR, Feigenson GW
JournalBiochemistry
PubMed ID7524658
The isothermal phase behavior of three gramicidin A'/phospholipid mixtures was investigated by an equilibrium Ca(2+)-binding technique. The phospholipid component was 1,2-dioleoyl-sn-glycero-3-phosphoserine (DOPS), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoserine (POPS), or POPS/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) at a constant mole ratio of 1/4. The bulk aqueous free Ca2+ concentration, [Ca2+]*f, in equilibrium with one or two gramicidin A'/phospholipid fluid ... More
Heterologous expression of human uteroglobin/polychlorinated biphenyl-binding protein. Determination of ligand binding parameters and mechanism of phospholipase A2 inhibition in vitro.
AuthorsAndersson O, Nordlund-Möller L, Barnes HJ, Lund J
JournalJ Biol Chem
PubMed ID7518449
High level expression of a human polychlorinated biphenyl-binding protein (hPCB-BP; also termed uteroglobin or CC10) was achieved in Escherichia coli. The recombinant protein (rhPCB-BP) constituted approximately 1% of total bacterial lysate proteins as judged from in vitro ligand binding assays using 4,4'-bis([3H]methylsulfonyl)-2,2',5,5'-tetrachlorobiphenyl. rhPCB-BP was purified to homogeneity in its native ... More
Novel action of BAPTA series chelators on intrinsic K+ currents in rat hippocampal neurones.
AuthorsLancaster B, Batchelor AM
JournalJ Physiol
PubMed ID10639100
1. Whole-cell recordings were made from rat CA1 neurones in brain slices. When electrodes contained diazo-2 (2 mM) or dibromo BAPTA (1 mM) a large steady-state outward current (hundreds of picoamps) developed within 5 min of breakthrough at a VH of -60 mV. BAPTA itself (1 mM) caused qualitatively similar ... More
Expression of apo-aequorin during embryonic development; how much is needed for calcium imaging?
AuthorsCréton R, Steele ME, Jaffe LF
JournalCell Calcium
PubMed ID9502193
Aequorin is a bioluminescent calcium indicator consisting of a 21 kDa protein (apo-aequorin) that is covalently linked to a lipophilic cofactor (coelenterazine). The aequorin gene can be expressed in a variety of cell lines and tissues, allowing non-invasive calcium imaging of specific cell types. In the present paper, we describe ... More
Rate of deactivation of nitric oxide-stimulated soluble guanylate cyclase: influence of nitric oxide scavengers and calcium.
AuthorsMargulis A, Sitaramayya A
JournalBiochemistry
PubMed ID10653648
Soluble guanylate cyclase (sGC) is highly activated by nitric oxide (NO) and is the known mediator of the effects of NO on a variety of physiological processes. The rates at which sGC is activated and deactivated are therefore of wide interest since they determine the duration of a tissue's response ... More
Photo-released intracellular Ca2+ rapidly blocks Ba2+ current in Lymnaea neurons.
AuthorsJohnson BD, Byerly L
JournalJ Physiol
PubMed ID8331587
1. The effect of intracellular Ca2+ on Ba2+ current flowing through voltage-dependent Ca2+ channels was studied using the whole-cell patch-clamp technique on isolated neurons from the snail Lymnaea stagnalis. Intracellular Ca2+ was increased by flash photolysis of the caged Ca2+ compound DM-nitrophen and measured with the optical indicator fluo-3. 2. ... More
Thermodynamics of metal ion binding and denaturation of a calcium binding protein from Entamoeba histolytica.
AuthorsGopal B, Swaminathan CP, Bhattacharya S, Bhattacharya A, Murthy MR, Surolia A
JournalBiochemistry
PubMed ID9283081
The thermodynamics of the binding of calcium and magnesium ions to a calcium binding protein from Entamoeba histolytica was investigated by isothermal titration calorimetry (ITC) in 20 mM MOPS buffer (pH 7.0) at 20 degrees C. Enthalpy titration curves of calcium show the presence of four Ca2+ binding sites. There ... More
Hydrophobic core substitutions in calbindin D9k: effects on Ca2+ binding and dissociation.
AuthorsKragelund BB, Jönsson M, Bifulco G, Chazin WJ, Nilsson H, Finn BE, Linse S
JournalBiochemistry
PubMed ID9636034
Hydrophobic core residues have a marked influence on the Ca2+-binding properties of calbindin D9k, even though there are no direct contacts between these residues and the bound Ca2+ ions. Eleven different mutants with substitutions in the hydrophobic core were produced, and their equilibrium Ca2+-binding constants measured from Ca2+ titrations in ... More
Tonotopic variations of calcium signalling in turtle auditory hair cells.
AuthorsRicci AJ, Gray-Keller M, Fettiplace R
JournalJ Physiol
PubMed ID10766923
Turtle cochlear hair cells are electrically tuned by a voltage-dependent Ca2+ current and a Ca2+-dependent K+ current (IBK(Ca)). The effects of intracellular calcium buffering on electrical tuning were studied in hair cells at apical and basal cochlear locations tuned to 100 and 300 Hz, respectively. Increasing the intracellular BAPTA concentration ... More
Calcium buffer injections delay cleavage in Xenopus laevis blastomeres.
AuthorsSnow P, Nuccitelli R
JournalJ Cell Biol
PubMed ID8320261
Microinjection of calcium buffers into the two-cell Xenopus laevis embryo delays cell division in a dose-dependent manner. Four calcium buffers in the BAPTA series with different affinities for calcium were used to distinguish between a localized calcium gradient regulating cleavage and the global calcium concentration regulating this event. DibromoBAPTA (Kd ... More
New calcium-sensitive ligand for nuclear magnetic resonance spectroscopy.
AuthorsRobitaille PM, Jiang Z
JournalBiochemistry
PubMed ID1472494
Fluorinated calcium-sensitive indicators such as 5,5'-difluoro-1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (difluoro-BAPTA) will often be less sensitive under in vivo conditions than gyromagnetic ratio considerations alone would have predicted. This is due to the very broad line widths displayed by these molecules within the living cell. In order to provide a spectroscopic alternative to ... More
Presynaptic calcium signals during neurotransmitter release: detection with fluorescent indicators and other calcium chelators.
AuthorsAugustine GJ, Adler EM, Charlton MP, Hans M, Swandulla D, Zipser K
JournalJ Physiol Paris
PubMed ID1364192
Synthetic calcium buffers, including fluorescent calcium indicators, were microinjected into squid 'giant' presynaptic nerve terminals to investigate the calcium signal that triggers neurotransmitter secretion. Digital imaging methods, applied in conjunction with the fluorescent calcium indicator dye fura-2, reveal that transient rises in presynaptic calcium concentration are associated with action potentials. ... More
Ligand binding specificities of the two mannose 6-phosphate receptors.
AuthorsSleat DE, Lobel P
JournalJ Biol Chem
PubMed ID8995357
Two mannose 6-phosphate (Man-6-P) receptors (MPRs) direct the vesicular transport of newly synthesized lysosomal enzymes that contain Man-6-P from the Golgi to a prelysosomal compartment. In order to understand the respective roles of the Mr = 46,000 cation-dependent (CD-) MPR and the Mr = 300,000 cation-independent (CI-) MPR in lysosomal ... More
Effect of temperature on receptor-activated changes in [Ca2+]i and their determination using fluorescent probes.
AuthorsShuttleworth TJ, Thompson JL
JournalJ Biol Chem
PubMed ID1988427
Several recent studies of intracellular Ca2+ concentration ([Ca2+]i using fluorescent indicators have involved experiments performed at nonphysiological temperatures, frequently room temperature. In the studies reported here, a reduction in temperature was shown to influence the measurement of [Ca2+]i in two major ways. The first is an effect on the value ... More
The high affinity calcium-binding sites in the epidermal growth factor module region of vitamin K-dependent protein S.
AuthorsStenberg Y, Linse S, Drakenberg T, Stenflo J
JournalJ Biol Chem
PubMed ID9287334
Vitamin K-dependent protein S, a cofactor of the anticoagulant enzyme-activated protein C, has four epidermal growth factor (EGF)-like modules, all of which have one partially hydroxylated Asp (EGF 1; beta-hydroxyaspartic acid) or Asn (EGF 2, 3, and 4; beta-hydroxyasparagine) residue. The three C-terminal modules have a typical Ca2+ binding sequence ... More