胰腺腺泡细胞中依赖Ca2(+)的淀粉酶分泌在不激活与磷脂酶C相连的G蛋白的情况下发生。
Ca2(+)-dependent amylase secretion from pancreatic acinar cells occurs without activation of phospholipase C linked G-proteins.
作者信息
Padfield P J, Ding T G, Jamieson J D
机构信息
Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510.
出版信息
Biochem Biophys Res Commun. 1991 Jan 31;174(2):536-41. doi: 10.1016/0006-291x(91)91450-q.
We have examined the influence of guanine nucleotides on Ca2(+)-dependent amylase secretion from SLO permeabilized rat pancreatic acini. GTP gamma S (100 microM) stimulated Ca2+ dependent amylase release, decreasing the EC50 for Ca2+ from 1.4 to 0.8 microM. By contrast, GDP (1mM) and dGDP (1mM) inhibited the maximal Ca2(+)-dependent secretory response. Measurement of IP3 liberation showed that Ca2+ stimulation did not increase the activity of phospholipase C (PLC) postulated to be linked to a G-protein termed Gp; GDP and dGDP must therefore be exerting their inhibitory action via a GTP-binding protein distinct from the PLC-linked Gp.
我们已经研究了鸟嘌呤核苷酸对经链球菌溶血素O（SLO）通透处理的大鼠胰腺腺泡细胞中Ca2+依赖的淀粉酶分泌的影响。GTPγS（100微摩尔）刺激了Ca2+依赖的淀粉酶释放，使Ca2+的半数有效浓度（EC50）从1.4微摩尔降至0.8微摩尔。相比之下，GDP（1毫摩尔）和dGDP（1毫摩尔）抑制了最大的Ca2+依赖的分泌反应。肌醇三磷酸（IP3）释放的测量结果表明，Ca2+刺激并没有增加假定与一种称为Gp的G蛋白相关联的磷脂酶C（PLC）的活性；因此，GDP和dGDP必定是通过一种不同于与PLC相关联的Gp的GTP结合蛋白发挥其抑制作用的。
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