Relation between crossbridge structure and actomyosin ATPase activity in rat heart.
Relation between crossbridge structure and actomyosin ATPase activity in rat heart.
复制标题
大鼠心脏横桥结构与肌动球蛋白 ATP 酶活性的关系。
DOI：
10.1161/01.res.83.1.60
复制
发表时间：
1998
影响因子：
20.1
通讯作者：
Winegrad,S
中科院分区：
文献类型：
--
作者：
Weisberg,A;Winegrad,S
- 心肌肌丝含有调节肌动蛋白和肌球蛋白之间相互作用的蛋白质。在粗丝中，有几种蛋白质可能有助于调节收缩。肌球蛋白结合蛋白C或C蛋白具有4个位点，其可被Ca 2 +-钙调蛋白控制的激酶、蛋白激酶A或蛋白激酶C磷酸化。用电镜和光学衍射技术研究了大鼠心室肌肌球蛋白重链（MHC）α和β亚型的粗肌丝结构以及C蛋白特异性磷酸化对粗肌丝结构的影响。在α-MHC的粗丝中，可以清楚地看到交叉桥。蛋白激酶A对C蛋白的磷酸化使横桥从细丝骨架延伸出来，改变了它们的方向，增加了横桥的有序度，并降低了横桥的柔性。具有β-MHC的微丝中的横桥较不有序，并且明显更灵活。在含有β-MHC的细丝中，C蛋白的磷酸化不会延长横桥，也不会改变有序度或柔性。从光学衍射图推断的横桥的相对灵活性与肌动球蛋白的ATP水解速率相关。这些结果表明：（1）横桥的柔韧性是确定横桥循环速率的重要参数;（2）C蛋白介导的对横桥位置和柔韧性的控制可能通过改变横桥循环的动力学来调节肌动球蛋白ATP酶活性。
—Cardiac myofilaments contain proteins that regulate the interaction between actin and myosin. In the thick filament, there are several proteins that may contribute to the regulation of the contraction. The myosin binding protein C, or C protein, has 4 sites that can be phosphorylated by a Ca2+-calmodulin–controlled kinase, protein kinase A or protein kinase C. Using electron microscopy and optical diffraction, we examined the structure of thick filaments isolated from rat ventricles with either the α or β isoform of myosin heavy chain (MHC) and the effect of specific phosphorylation of C protein on the structure. In thick filaments with α-MHC, crossbridges were clearly visible. Phosphorylation of C protein by protein kinase A extended the crossbridges from the backbone of the filament, changed their orientation, increased the degree of order of the crossbridges, and decreased the flexibility of the crossbridges. Crossbridges in filaments with β-MHC were less ordered and apparently more flexible. Phosphorylation of C protein in β-MHC–containing filaments did not extend the crossbridges and did not alter degree of order or flexibility. The relative flexibility of the crossbridges inferred from the optical diffraction pattern correlated well with the rate of ATP hydrolysis by actomyosin. These results suggest that (1) crossbridge flexibility is an important parameter in setting the rate of crossbridge cycling, and (2) C protein–mediated control of the position and flexibility of crossbridges may regulate actomyosin ATPase activity by modifying the kinetics of crossbridge cycling.
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影响因子：
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作者：
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DOI：
--
发表时间：
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期刊：
影响因子：
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