Characterization of actin filament severing by actophorin from Acanthamoeba castellanii.
Characterization of actin filament severing by actophorin from Acanthamoeba castellanii.
复制标题
acanthamoeba castellanii的肌动蛋白丝的肌动蛋白丝的表征。
DOI：
10.1083/jcb.115.6.1611
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发表时间：
1991-12
期刊：
影响因子：
--
通讯作者：
Pollard TD
中科院分区：
文献类型：
--
作者：
Maciver SK;Zot HG;Pollard TD
Actophorin是一种来自棘阿米巴的丰富的15-kD的肌动蛋白结合蛋白，被认为与肌动蛋白单体形成不可聚合的复合物，并通过切断细丝来降低聚合肌动蛋白的粘度（Cooper等，1986）。生物。化学261:477 - 485)。同源蛋白已在海胆、鸡和哺乳动物组织中发现。化学交联产生1:1的肌动蛋白和动蛋白共价复合物。肌动蛋白和profilin相互竞争与肌动蛋白单体交联。动态蛋白对肌动蛋白聚合物稳态浓度的影响使得动态蛋白与肌动蛋白单体复合物的Kd值为0.2微米。一些新的证据，包括对肌动蛋白丝末端的延伸率和解聚率的测定，表明动蛋白在稳态和自发聚合过程中都切断了肌动蛋白丝。光镜下的直接观察证实了这一点，并表明，肌动蛋白对聚合肌动蛋白的低剪切粘度的影响不能用单体隔离来解释。在化学计量浓度的phalloidin或毫摩尔浓度的无机磷酸盐的作用下，actophorin的切断活性被强烈抑制。
Actophorin is an abundant 15-kD actinbinding protein from Acanthamoeba that is thought to form a nonpolymerizable complex with actin monomers and also to reduce the viscosity of polymerized actin by severing filaments (Cooper et al., 1986. J. Biol. Chem. 261:477-485). Homologous proteins have been identified in sea urchin, chicken, and mammalian tissues. Chemical crosslinking produces a 1:1 covalent complex of actin and actophorin. Actophorin and profilin compete for crosslinking to actin monomers. The influence of actophorin on the steady-state actin polymer concentration gave a Kd of 0.2 microM for the complex of actophorin with actin monomers. Several new lines of evidence, including assays for actin filament ends by elongation rate and depolymerization rate, show that actophorin severs actin filaments both at steady state and during spontaneous polymerization. This is confirmed by direct observation in the light microscope and by showing that the effects of actophorin on the low shear viscosity of polymerized actin cannot be explained by monomer sequestration. The severing activity of actophorin is strongly inhibited by stoichiometric concentrations of phalloidin or millimolar concentrations of inorganic phosphate.