Evidence for a role of myosin phosphorylation in the initiation of the platelet shape change response.
Evidence for a role of myosin phosphorylation in the initiation of the platelet shape change response.
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DOI：
10.1016/s0021-9258(17)42774-8
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发表时间：
1984-08
期刊：
影响因子：
--
通讯作者：
J. Daniel;I. Molish;M. Rigmaiden;G. Stewart
中科院分区：
文献类型：
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作者：
J. Daniel;I. Molish;M. Rigmaiden;G. Stewart
当用ADP刺激血小板引起形状改变而不聚集或分泌时，肌球蛋白20，000-Da轻链磷酸化迅速，并且似乎略微先于形状改变反应。虽然血小板的形状保持球形，但肌球蛋白磷酸化是短暂的，2-5分钟后恢复到与未刺激细胞相同的水平。在这些条件下，47，000-Da血小板蛋白的磷酸化是最小的。加入吲哚美辛或使细胞聚集并不改变磷酸化时间进程。肌球蛋白磷酸化的剂量反应曲线与形状变化的曲线非常接近，中点在0.7 μ M ADP。ATP是ADP的竞争性拮抗剂，在相同浓度下，ATP对肌球蛋白的磷酸化和形状改变均产生50%的抑制作用。同样地，当血小板被15-羟基-9，11-偶氮-二十二碳二烯酸或胶原蛋白刺激时，肌球蛋白磷酸化稍早于形状改变。这些结果表明，肌球蛋白磷酸化是血小板形状的初始变化所必需的，但不是维持球形所必需的。
When platelets were stimulated with ADP to cause shape change without aggregation or secretion, myosin 20,000-Da light chain phosphorylation was rapid and appeared to precede slightly the shape change response. While the shape of the platelets remained spheroidal, myosin phosphorylation was transient and after 2-5 min returned to the same level as that of unstimulated cells. Phosphorylation of the 47,000-Da platelet protein was minimal under these conditions. The phosphorylation time course was not altered by the addition of indomethacin or allowing the cells to aggregate. The dose-response curve of myosin phosphorylation very closely paralleled that of shape change with a midpoint at 0.7 microM ADP. ATP, a competitive antagonist of ADP, inhibited both shape change and myosin phosphorylation with the same concentration of ATP causing 50% inhibition of each response. Similarly, when platelets were stimulated with either 15-hydroxy-9,11-azo-prostadienoic acid or collagen, myosin phosphorylation slightly preceded shape change. These results suggest that myosin phosphorylation is required for the initial change in platelet shape but is not necessary for maintenance of the spherical shape.