Polarized Ca2+ release in saponin-permeabilized parotid acinar cells evoked by flash photolysis of 'caged' inositol 1,4,5-trisphosphate.
AuthorsTanimura A, Matsumoto Y, Tojyo Y
JournalBiochem J
PubMed ID9620881
'In exocrine acinar cells, agonist stimulation results in a polarized Ca2+ signal, termed the ''Ca2+ wave'', that propagates from the apical pole towards the basolateral region. We attempted to detect the inositol 1,4,5-trisphosphate (InsP3)-induced Ca2+ wave in saponin-permeabilized rat parotid acinar cells using a digital imaging system. The permeabilized acinar ... More
Ion selectivities of the Ca(2+) sensors for exocytosis in rat phaeochromocytoma cells.
AuthorsKishimoto T, Liu TT, Ninomiya Y, Takagi H, Yoshioka T, Ellis-Davies GC, Miyashita Y, Kasai H
JournalJ Physiol
PubMed ID11410622
'1. The ion selectivities of the Ca(2+) sensors for the two components of exocytosis in rat phaeochromocytoma (PC12) cells were examined by measurement of membrane capacitance and amperometry. The cytosolic concentrations of metal ions were increased by photolysis of caged-Ca(2+) compounds and measured with low-affinity indicators benzothiazole coumarin (BTC) or ... More
Multiple zinc binding sites in retinal rod cGMP phosphodiesterase, PDE6alpha beta.
AuthorsHe F, Seryshev AB, Cowan CW, Wensel TG
JournalJ Biol Chem
PubMed ID10787404
'The photoreceptor cGMP phosphodiesterase (PDE6) plays a key role in vertebrate vision, but its enzymatic mechanism and the roles of metal ion co-factors have yet to be determined. We have determined the amount of endogenous Zn(2+) in rod PDE6 and established a requirement for tightly bound Zn(2+) in catalysis. Purified ... More
Control of InsP3-induced Ca2+ oscillations in permeabilized blowfly salivary gland cells: contribution of mitochondria.
AuthorsZimmermann B
JournalJ Physiol
PubMed ID10856123
'Many agonists linked to the generation of inositol 1,4, 5-trisphosphate (InsP3) and release of Ca2+ from intracellular stores induce repetitive transients in cytosolic Ca2+ whose frequency increases over a certain range of agonist concentrations. In order to investigate the mechanisms underlying this frequency modulation, the fluorescent Ca2+ sensor mag-fura-2 was ... More
GAP, an aequorin-based fluorescent indicator for imaging Ca2+ in organelles.
AuthorsRodriguez-Garcia A, Rojo-Ruiz J, Navas-Navarro P, Aulestia FJ, Gallego-Sandin S, Garcia-Sancho J, Alonso MT,
Journal
PubMed ID24501126
Genetically encoded calcium indicators allow monitoring subcellular Ca(2+) signals inside organelles. Most genetically encoded calcium indicators are fusions of endogenous calcium-binding proteins whose functionality in vivo may be perturbed by competition with cellular partners. We describe here a novel family of fluorescent Ca(2+) sensors based on the fusion of two ... More
Structural analysis of a calmodulin variant from rice: the C-terminal extension of OsCaM61 regulates its calcium binding and enzyme activation properties.
OsCaM61 is one of five calmodulins known to be present in Oryza sativa that relays the increase of cytosolic [Ca(2+)] to downstream targets. OsCaM61 bears a unique C-terminal extension with a prenylation site. Using nuclear magnetic resonance (NMR) spectroscopy we studied the behavior of the calmodulin (CaM) domain and the ... More
STIM1 gates the store-operated calcium channel ORAI1 in vitro.
AuthorsZhou Y, Meraner P, Kwon HT, Machnes D, Oh-hora M, Zimmer J, Huang Y, Stura A, Rao A, Hogan PG,
JournalNat Struct Mol Biol
PubMed ID20037597
Store-operated Ca(2+) entry through the plasma membrane Ca(2+) release-activated Ca(2+) (CRAC) channel in mammalian T cells and mast cells depends on the sensor protein stromal interaction molecule 1 (STIM1) and the channel subunit ORAI1. To study STIM1-ORAI1 signaling in vitro, we have expressed human ORAI1 in a sec6-4 strain of ... More
Notch activity acts as a sensor for extracellular calcium during vertebrate left-right determination.
AuthorsRaya A, Kawakami Y, Rodríguez-Esteban C, Ibañes M, Rasskin-Gutman D, Rodríguez-León J, Büscher D, Feijó JA, Izpisúa Belmonte JC
JournalNature
PubMed ID14712268
During vertebrate embryo development, the breaking of the initial bilateral symmetry is translated into asymmetric gene expression around the node and/or in the lateral plate mesoderm. The earliest conserved feature of this asymmetric gene expression cascade is the left-sided expression of Nodal, which depends on the activity of the Notch ... More
Inositol 1,4,5-trisphosphate-dependent oscillations of luminal [Ca2+] in permeabilized HSY cells.
AuthorsTanimura A, Turner RJ
JournalJ Biol Chem
PubMed ID8940075
Oscillations in intracellular Ca2+ concentration ([Ca2+]i) are thought to play an important role in phosphoinositide-linked Ca2+ signaling events. We demonstrate corresponding inositol 1,4, 5-trisphosphate (IP3)-dependent oscillations of Ca2+ concentration within the lumen of the IP3-sensitive stores ([Ca2+]L) of saponin-permeabilized HSY cells by monitoring [Ca2+]L with the fluorescent Ca2+ indicator Mag-fura-2. ... More
Localized detection of action potential-induced presynaptic calcium transients at a Xenopus neuromuscular junction.
AuthorsDiGregorio DA, Vergara JL
JournalJ Physiol
PubMed ID9457637
1. Action potential (AP)-induced fluorescence transients were measured, using Ca2+ indicators and a spot-detection method, at single nerve terminals of a cultured Xenopus neuromuscular junction preparation with simultaneous measurement of neurotransmitter release. 2. Transients obtained using the low affinity Ca2+ indicator Oregon Green 488 BAPTA-5N (OGB-5N) exhibited rapid rising (t1/2 ... More
The intraacrosomal calcium pool plays a direct role in acrosomal exocytosis.
AuthorsDe Blas G, Michaut M, Treviño CL, Tomes CN, Yunes R, Darszon A, Mayorga LS
JournalJ Biol Chem
PubMed ID12379648
The acrosome reaction is a unique type of regulated exocytosis. The single secretory granule of the sperm fuses at multiple points with the overlying plasma membrane. In the past few years we have characterized several aspects of this process using streptolysin O-permeabilized human spermatozoa. Here we show that Rab3A triggers ... More