Enouf J, Bredoux R, Bourdeau N, Giraud F, Le Peuch C, Lebret M, Levy-Toledano S
Unité de Recherches sur la Thrombose expérimentale et l'Hémostase, INSERM U150, CNRS UA334, Hôpital Lariboisière, Paris, France.
Biochimie. 1987 Apr;69(4):297-304. doi: 10.1016/0300-9084(87)90020-4.
The effect of cAMP (which involved a 23 kDa protein phosphorylation) has been studied on the Ca2+ uptake and Ca2+ release from a human platelet membrane vesicle fraction. It was tested in the presence of the catalytic subunit of the cAMP-dependent protein kinase (C Sub). The addition of C Sub increased the steady state level of the Ca2+ uptake into the membrane vesicles. The effect was enhanced when tested in the absence of Ca2+ precipitating agent. The response was proportional to the dose of C Sub. Moreover, the effect varied with the Ca2+ concentration. The effect of C Sub has been tested on the inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release. A phosphorylated state of the 23 kDa protein appeared to be necessary. Indeed, a phosphorylation inhibition prevented the IP3 effect and the addition of C Sub increased the percentage of released Ca2+ (without modification of the time course). However, the C Sub dose-dependent response was not linear. The effect of cAMP on the two functions (Ca2+ uptake and Ca2+ release) appears to be different. Therefore, these results led us to suggest a more complex role of cAMP in the regulation of platelet Ca2+ concentration.
已研究了环磷酸腺苷（cAMP，其涉及一种23 kDa蛋白的磷酸化）对人血小板膜囊泡组分摄取Ca2+和释放Ca2+的影响。在存在环磷酸腺苷依赖性蛋白激酶催化亚基（C亚基）的情况下进行了测试。添加C亚基可提高膜囊泡中Ca2+摄取的稳态水平。在不存在Ca2+沉淀剂的情况下进行测试时，该效应增强。反应与C亚基的剂量成正比。此外，效应随Ca2+浓度而变化。已测试了C亚基对肌醇1,4,5 -三磷酸（IP3）诱导的Ca2+释放的影响。23 kDa蛋白的磷酸化状态似乎是必需的。确实，磷酸化抑制可阻止IP3效应，而添加C亚基可增加释放的Ca2+百分比（不改变时间进程）。然而，C亚基的剂量依赖性反应并非呈线性。cAMP对这两种功能（Ca2+摄取和Ca2+释放）的影响似乎有所不同。因此，这些结果使我们认为cAMP在调节血小板Ca2+浓度方面具有更复杂的作用。
