Mechanistic and Functional Aspects of Oscillatory Calcium Signalling
Mobilization of calcium from intracellular stores and the extracellular medium to yield an increase in cytosolic free Ca2+ ([Ca2+]i) is one of the most common forms of signal transduction utilized by extracellular stimuli in the control of cell function. It is now clear that receptor-induced increases in [Ca2+]i are generated, in part, by an elevation in the level of the second messenger inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) which is produced by a phospholipase C (PLC)-mediated hydrolysis of phosphatidyl inositol 4,5-bisphosphate (Berridge and Irvine, 1984). Ins(1,4,5)P3 is released into the cytosol where it interacts with an intracellular receptor which functions as a release channel for lumenal Ca2+ (Berridge and Irvine, 1989; Joseph and Williamson, 1989). However, intracellular Ca2+ stores are not uniformly sensitive to Ins(1,4,5)P3, as demonstrated in permeabilized cell studies where Ins(1,4,5)P3 can only release a fraction (30–50%) of the calcium accumulated by non-mitochondrial stores (Berridge and Irvine, 1984; Williamson et al., 1985; Joseph and Williamson, 1989). There is some debate as to the intracellular location of the Ins(1,4,5)P3-sensitive Ca2+ store. In Purkinje cells antibodies to the receptor have revealed localized concentrations on the nuclear envelope and parts of the endoplasmic reticulum (E.R.) (Ross etal., 1989).
KeywordsAngiotensin Histamine Gallione Cytosol Washout
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- Berridge MJ (1988) Inositol trisphosphate-induced membrane potential oscillations in Xenopus oocytes. J Physiol (Lond) 403:589–599Google Scholar
- Rooney TA, Renard DC, Sass E, Thomas AP (1991) Oscillatory cytosolic calcium waves independent of stimulated inositol 1,4,5-trisphosphate formation in hepatocytes. J Biol Chem (In press)Google Scholar
- Volpe P, Krause K-H, Hashimoto S, Zorzato F, Pozzan T, Meldolesi J, Lew DP (1988) “Calciosome,”a cytoplasmic organelle: the inositol 1,4,5-trisphosphate-sensitive Ca2+ store of nonmuscle cells? Proc Natl Acad Sci USA 85:1091–1095 Wakui M, Potter BVL, Peterson OH (1989) Pulsatile intracellular calcium release does not depend on fluctuations in inositol trisphosphate concentration. Nature (Lond) 339:317–320Google Scholar