Streb H, Irvine R F, Berridge M J, Schulz I
Nature. 1983;306(5938):67-9. doi: 10.1038/306067a0.
Activation of receptors for a wide variety of hormones and neurotransmitters leads to an increase in the intracellular level of calcium. Much of this calcium is released from intracellular stores but the link between surface receptors and this internal calcium reservoir is unknown. Hydrolysis of the phosphoinositides, which is another characteristic feature of these receptors, has been implicated in calcium mobilization. The primary lipid substrates for the receptor mechanism seem to be two polyphosphoinositides, phosphatidylinositol 4-phosphate (PtdIns4P) and phosphatidylinositol 4,5-bisphosphate (PtdIns4,5P2), which are rapidly hydrolysed following receptor activation in various cells and tissues. The action of phospholipase C on these polyphosphoinositides results in the rapid formation of the water-soluble products inositol 1,4-bisphosphate (Ins1,4P2) and inositol 1,4,5-trisphosphate (Ins1,4,5P3). In the insect salivary gland, where changes in Ins1,4P2 and Ins1,4,5P2 have been studied at early time periods, increases in these inositol phosphates are sufficiently rapid to suggest that they might mobilize internal calcium. We report here that micromolar concentrations of Ins1,4,5P3 release Ca2+ from a nonmitochondrial intracellular Ca2+ store in pancreatic acinar cells. Our results strongly suggest that this is the same Ca2+ store that is released by acetylcholine.
多种激素和神经递质的受体激活会导致细胞内钙水平升高。这种钙大部分从细胞内储存库释放，但表面受体与这个内部钙储存库之间的联系尚不清楚。磷酸肌醇的水解是这些受体的另一个特征，与钙动员有关。受体机制的主要脂质底物似乎是两种多磷酸肌醇，磷脂酰肌醇4-磷酸（PtdIns4P）和磷脂酰肌醇4,5-二磷酸（PtdIns4,5P2），在各种细胞和组织中受体激活后它们会迅速水解。磷脂酶C对这些多磷酸肌醇的作用导致水溶性产物肌醇1,4-二磷酸（Ins1,4P2）和肌醇1,4,5-三磷酸（Ins1,4,5P3）的快速形成。在昆虫唾液腺中，已经在早期阶段研究了Ins1,4P2和Ins1,4,5P2的变化，这些肌醇磷酸的增加足够迅速，表明它们可能动员内部钙。我们在此报告，微摩尔浓度的Ins1,4,5P3从胰腺腺泡细胞的非线粒体细胞内钙储存库中释放Ca2+。我们的结果强烈表明，这与乙酰胆碱释放的是同一个钙储存库。
