ISSN:
0730-2312
Keywords:
pancreatic β cell
;
insulin secretion
;
Ca2+ channel
;
exocytosis
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Insulin secretion is triggered by a rise in the intracellular Ca2+ concentration that results from the activation of voltage-gated Ca2+ channels in the β-cell plasma membrane. Multiple types of β-cell Ca2+ channel have been identified in both electrophysiological and molecular biological studies, but it appears that the L-type Ca2+ channel plays a dominant role in regulating Ca2+ influx. Activity of this channel is potentiated by protein kinases A and C and is inhibited by GTP-binding proteins, which may mediate the effects of potentiators and inhibitors of insulin secretion on Ca2+ influx, respectively. The mechanism by which elevation of intracellular Ca2+ leads to the release of insulin granules is not fully understood but appears to involve activation of Ca2+/calmodulin-dependent protein kinase. Phosphorylation by either protein kinase A or C, probably at different substrates, potentiates insulin secretion by acting at some late stage in the secretory process. There is also evidence that small GTP-binding proteins are involved in regulating exocytosis in β cells. The identification and characterisation of the proteins involved in exocytosis in β cells and clarification of the mechanism(s) of action of Ca2+ is clearly an important goal for the future. © 1994 Wiley-Liss, Inc.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcb.240550007
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