INTERACTION OF C-PROTEIN WITH MYOSIN, MYOSIN ROD AND LIGHT-MEROMYOSIN
INTERACTION OF C-PROTEIN WITH MYOSIN, MYOSIN ROD AND LIGHT-MEROMYOSIN
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DOI：
10.1016/s0022-2836(75)80017-9
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发表时间：
1975-01-01
影响因子：
5.6
通讯作者：
BENNETT, P
中科院分区：
文献类型：
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作者：
MOOS, C;OFFER, G;BENNETT, P
C 蛋白是脊椎动物骨骼肌肌原纤维的组成部分，已知位于含有肌球蛋白的粗肌丝的特定位置。我们研究了它对肌球蛋白体外组装成丝的影响，以及它与低离子强度聚集体肌球蛋白杆和轻肌球蛋白（肌球蛋白的α螺旋片段）的相互作用。C蛋白对于体外肌球蛋白丝的形成不是必需的。纯化的肌球蛋白不含 C 蛋白，可以形成具有明显 14 nm 纵向重复的长丝。 C 蛋白的存在破坏了肌球蛋白丝结构的规律性，导致直径减小且变化更大，以及纵向顺序的丧失。然而，C 蛋白似乎不具有任何长度调节作用。低离子强度下的结合测量表明，C 蛋白对肌球蛋白以及杆状肌球蛋白和轻肌球蛋白具有很强的亲和力。对于肌球蛋白，结合的限制化学计量约为每摩尔一摩尔C-蛋白，而对于杆状和轻质肌球蛋白则稍少。还通过电子显微镜研究了C-蛋白与杆状和轻质肌球蛋白的相互作用。在没有 C 蛋白的情况下，肌球蛋白棒形成具有 14 nm 纵向重复的大片状副晶体。当 C 蛋白存在时，这些副晶体的形成被破坏，在它们的位置上我们发现了不规则的窄丝。轻质肌球蛋白副晶体的形成不会被 C 蛋白破坏。 C蛋白在副晶体上形成一系列横向条纹，其纵向间距与约40 nm的主要重复相同，其表征了轻的meromyosin组装。我们得出的结论是，天然粗丝中的 C 蛋白可能以由底层肌球蛋白组装决定的周期性结合到丝的轴上。
C-protein, a component of vertebrate skeletal muscle myofibrils, is known to be located at specific positions along the thick myosin-containingc myofilaments. We have investigated its effects on the assembly of myosin into filamentsin vitroand its interaction with low ionic strength aggregates of myosin rod and light meromyosin, the α-helical fragments of myosin.C-protein is not required for the formation of myosin filamentsin vitro. Purified myosin, free of C-protein, can form long filaments with a demonstrable 14 nm longitudinal repeat. The presence of C-protein disrupts the regularity of the myosin filament structure, resulting in a reduced and more variable diameter and a loss of longitudinal order. However, C-protein does not appear to have any length-regulating role.Binding measurements at low ionic strength reveal a strong affinity of C-protein for myosin and also for rod and light meromyosin. The limiting stoichiometry of binding is about one mole C-protein per mole for myosin and somewhat less for rod and light meromyosin.The interaction of C-protein with rod and light meromyosin has also been investigated by electron microscopy. In the absence of C-protein, myosin rod forms large sheet-like paracrystals with a 14 nm longitudinal repeat. In the presence of C-protein the formation of these paracrystals is disrupted and in their place we find irregular narrow filaments. Formation of paracrystals of light meromyosin is not disrupted by C-protein. The C-protein forms a series of transverse stripes on the paracrystal with a longitudinal spacing identical to the principal repeat of about 40 nm which characterizes the light meromyosin assembly. We conclude that the C-protein in native thick filaments is probably bound to the shaft of the filament with a periodicity determined by the underlying myosin assembly.