Epstein H F, Aronow B J, Harris H E
J Supramol Struct. 1975;3(4):354-60. doi: 10.1002/jss.400030407.
The interaction of myosin and paramyosin was investigated by enzymological and ultrastructural techniques. The actin-activated Mg+2 ATPase of rabbit skeletal muscle myosin can be inhibited by clam adductor paramyosin. Both proteins must be rapidly coprecipitated to form filaments for this inhibition. Slowly formed cofilaments are fully activatable by F-actin. In both cases, the cofilaments possess unique structural characteristics when compared to homofilaments. The mode of inhibition appears to be competitive when different concentrations of paramyosin and F-actin are compared. The apparent affinity of the myosin heads for actin is reduced by the presence of paramyosin within rapidly reconstituted thick filaments. These results suggest that paramyosin may serve as part of a relaxing mechanism within invertebrate muscles. It is unlikely that paramyosin plays a role in the initiation and maintenance of catch within specialized molluscan muscles.
采用酶学和超微结构技术研究了肌球蛋白与副肌球蛋白的相互作用。蛤类闭壳肌副肌球蛋白可抑制兔骨骼肌肌球蛋白的肌动蛋白激活的Mg+2 ATP酶。为实现这种抑制，两种蛋白质必须迅速共沉淀形成细丝。缓慢形成的共丝可被F-肌动蛋白完全激活。在这两种情况下，与同型丝相比，共丝具有独特的结构特征。当比较不同浓度的副肌球蛋白和F-肌动蛋白时，抑制模式似乎是竞争性的。在快速重构的粗丝中，副肌球蛋白的存在降低了肌球蛋白头部对肌动蛋白的表观亲和力。这些结果表明，副肌球蛋白可能是无脊椎动物肌肉舒张机制的一部分。副肌球蛋白不太可能在特殊软体动物肌肉的捕获启动和维持中发挥作用。
