Activating calcium release through inositol 1,4,5-trisphosphate receptors without inositol 1,4,5-trisphosphate

摘要

Cytosolic calcium (Ca~2+) is a focal point of many signal transduction pathways and modulates a diverse array of cellular activities ranging from fertile- ization to cell death (1). Cells generate Ca~2+ signals through both internal and external Ca~2+ sources. In most cell types, the major internal Ca~2+ stores are the endoplasmic reticulum/sarcoplasmic re- ticulum (ER/SR). One mechanism for mobilizing such stores involves the clas- sical phosphoinositide pathway. Essen- tially, the binding of many hormones to specific receptors on the plasma mem- brane leads to the activation of an en- zyme (phosphoinositidase C) that catal- yses the hydrolysis of phospholipids to produce the intracellular messenger ino- sitol 1,4,5-trisphosphate (InsP_3).