Panasenko O O, Gusev N B
Department of Biochemistry, School of Biology, Moscow State University, Russia.
IUBMB Life. 2000 Apr;49(4):277-82. doi: 10.1080/15216540050033131.
Interaction of calponin and alpha-actinin with actin was analyzed by means of cosedimentation and electron microscopy. G-actin was polymerized in the presence of calponin, alpha-actinin, or both of these actin-binding proteins (ABPs). The single and bundled actin filaments were separated, and the stoichiometry of ABPs and actin in both types of filaments was determined. Binding of calponin to the single or bundled actin filaments was not dependent on the presence of alpha-actinin and did not displace alpha-actinin from actin. In the presence of calponin, however, less alpha-actinin was bound to the bundled actin filaments, and the binding of alpha-actinin was accompanied by a partial decrease in the calponin/actin stoichiometry in the bundles of actin filaments. Calponin had no influence on the binding of alpha-actinin to the single actin filaments. The structure of actin bundles formed in the presence of the two ABPs differed from that formed in the presence of either one singly. We conclude that calponin and alpha-actinin can coexist on actin and that nearly each actin monomer can bind one of these ABPs.
通过共沉降和电子显微镜分析了钙调蛋白和平滑肌α辅肌动蛋白与肌动蛋白的相互作用。G-肌动蛋白在钙调蛋白、平滑肌α辅肌动蛋白或这两种肌动蛋白结合蛋白（ABP）存在的情况下发生聚合。分离出单根和成束的肌动蛋白丝，并确定了这两种类型丝中ABP与肌动蛋白的化学计量比。钙调蛋白与单根或成束的肌动蛋白丝的结合不依赖于平滑肌α辅肌动蛋白的存在，也不会将平滑肌α辅肌动蛋白从肌动蛋白上取代。然而，在钙调蛋白存在的情况下，较少的平滑肌α辅肌动蛋白与成束的肌动蛋白丝结合，并且平滑肌α辅肌动蛋白的结合伴随着肌动蛋白丝束中钙调蛋白/肌动蛋白化学计量比的部分降低。钙调蛋白对平滑肌α辅肌动蛋白与单根肌动蛋白丝的结合没有影响。在两种ABP存在的情况下形成的肌动蛋白束的结构与单独存在任何一种ABP时形成的结构不同。我们得出结论，钙调蛋白和平滑肌α辅肌动蛋白可以在肌动蛋白上共存，并且几乎每个肌动蛋白单体都可以结合这些ABP中的一种。
