Shimo-Oka T, Ohnishi K, Watanabe Y
J Biochem. 1983 Apr;93(4):977-87. doi: 10.1093/oxfordjournals.jbchem.a134253.
Crude actomyosin fraction from porcine brain contained a large amount of high molecular weight actin-binding protein (BABP). The molar ratio of BABP to actin (BABP/actin) in the fraction was estimated to be 0.22. From this fraction, BABP and actin were solubilized with a molar ratio of 0.25, suggesting the existence of an interaction between BABP and brain actin. BABP was finally purified to 90% purity. The purified BABP was negatively stained and observed by electron microscopy; it appeared to be a slender, flexible, two-stranded molecule whose contour length was about 200 nm. The structure was very similar to those of fodrin and other high molecular weight actin-binding proteins such as filamin, spectrin, and ABP. Lattice cage-like structures composed of BABP molecules were occasionally observed at high BABP concentrations. The addition of BABP to actin filaments resulted in the appearance of many branching, filamentous bundles. The electron microscopic observations suggested that a single BABP molecule could crosslink actin filaments, that is, one BABP molecule has two actin binding sites.
猪脑粗肌动球蛋白组分含有大量高分子量肌动蛋白结合蛋白（BABP）。该组分中BABP与肌动蛋白的摩尔比（BABP/肌动蛋白）估计为0.22。从该组分中，BABP和肌动蛋白以0.25的摩尔比溶解，这表明BABP与脑肌动蛋白之间存在相互作用。BABP最终被纯化至90%的纯度。纯化后的BABP经负染后用电子显微镜观察；它看起来是一个细长、灵活的双链分子，其轮廓长度约为200纳米。其结构与血影蛋白以及其他高分子量肌动蛋白结合蛋白如细丝蛋白、血影蛋白和ABP非常相似。在高BABP浓度下偶尔会观察到由BABP分子组成的晶格笼状结构。向肌动蛋白丝中添加BABP会导致出现许多分支的丝状束。电子显微镜观察表明，单个BABP分子可以交联肌动蛋白丝，也就是说，一个BABP分子有两个肌动蛋白结合位点。
