Enouf J, Giraud F, Bredoux R, Bourdeau N, Levy-Toledano S
Biochim Biophys Acta. 1987 Apr 2;928(1):76-82. doi: 10.1016/0167-4889(87)90087-5.
The addition of inositol 1,4,5-trisphosphate (IP3) to a 45Ca-preloaded human platelet membrane fraction (dense tubular system) induced a transient release of Ca2+. When the vesicle fraction was loaded with 45Ca2+ to isotopic equilibrium in the presence of the catalytic subunit of the cAMP-dependent protein kinase, the level of Ca2+ uptake was increased and the subsequent IP3-induced Ca2+ release was enhanced. The stimulation was observed regardless of the IP3 concentration used, and was maximal with an enzyme concentration of 5 micrograms/ml. The addition of the protein kinase inhibitor prevented the stimulatory effect of the catalytic subunit on IP3-induced calcium release, and also abolished the calcium release detected in the absence of added enzyme. It is concluded that a cAMP-dependent protein phosphorylation may be involved in the regulation of the IP3-induced Ca2+ release in human platelets.
向预先加载了45Ca的人血小板膜部分（致密管状系统）中添加肌醇1,4,5-三磷酸（IP3）会诱导Ca2+的瞬时释放。当囊泡部分在cAMP依赖性蛋白激酶催化亚基存在下加载45Ca2+至同位素平衡时，Ca2+摄取水平增加，随后IP3诱导的Ca2+释放增强。无论使用的IP3浓度如何，均观察到这种刺激作用，在酶浓度为5微克/毫升时达到最大。添加蛋白激酶抑制剂可阻止催化亚基对IP3诱导的钙释放的刺激作用，并且还消除了在未添加酶时检测到的钙释放。结论是cAMP依赖性蛋白磷酸化可能参与人血小板中IP3诱导的Ca2+释放的调节。
