Pollard T D, Tseng P C, Rimm D L, Bichell D P, Williams R C, Sinard J, Sato M
Cell Motil Cytoskeleton. 1986;6(6):649-61. doi: 10.1002/cm.970060613.
Characterization of a protein from Acanthamoeba that was originally called gelation protein [T.D. Pollard, J. Biol. Chem. 256:7666-7670, 1981] has shown that it resembles the actin filament cross-linking protein, alpha-actinin, found in other cells. It comprises about 1.5% of the total amoeba protein and can be purified by chromatography with a yield of 13%. The native protein has a molecular weight of 180,000 and consists of two polypeptides of 90,000 Da. The Stokes' radius is 8.5 nm, the intrinsic viscosity is 0.35 dl/dm, and the extinction coefficient at 280 mm is 1.8 X 10(5)M-1 X cm-1. Electron micrographs of shadowed specimens show that the molecule is a rod 48 nm long and 7 nm wide with globular domains at both ends and in the middle of the shaft. On gel electrophoresis in sodium dodecylsulfate the pure protein can run as bands with apparent molecular weights of 60,000, 90,000, 95,000, or 134,000 depending on the method of sample preparation. Rabbit antibodies to electrophoretically purified Acanthamoeba alpha-actinin polypeptides react with all of these electrophoretic variants in samples of purified protein and cell extracts. By indirect fluorescent antibody staining of fixed amoebas, alpha-actinin is distributed throughout the cytoplasmic matrix and concentrated in the hyaline cytoplasm of the cortex. The protein cross-links actin filaments in the presence and absence of Ca++. It inhibits slightly the time course of the spontaneous polymerization of actin monomers but has no effect on the critical concentration for actin polymerization even though it increases the apparent rate of elongation to a small extent. Like some other cross-linking proteins, amoeba alpha-actinin inhibits the actin-activated ATPase of muscle myosin subfragment-1. Although Acanthamoeba alpha-actinin resembles the alpha-actinin from other cells in shape and ability to cross-link actin filaments, antibodies to amoeba and smooth muscle alpha-actinins do not cross react and there are substantial differences in the amino acid compositions and molecular dimensions.
对一种最初被称为凝胶化蛋白的棘阿米巴属蛋白质的特性研究[T.D.波拉德，《生物化学杂志》256:7666 - 7670，1981]表明，它类似于在其他细胞中发现的肌动蛋白丝交联蛋白α - 辅肌动蛋白。它约占阿米巴总蛋白的1.5%，可通过色谱法纯化，产率为13%。天然蛋白的分子量为180,000，由两条90,000 Da的多肽组成。斯托克斯半径为8.5 nm，特性粘度为0.35 dl/dm，在280 nm处的消光系数为1.8×10(5)M - 1×cm - 1。经投影的标本的电子显微镜照片显示，该分子是一个长48 nm、宽7 nm的杆状结构，两端和杆中部有球状结构域。在十二烷基硫酸钠凝胶电泳中，根据样品制备方法的不同，纯蛋白可呈现表观分子量为60,000、90,000、95,000或134,000的条带。针对经电泳纯化的棘阿米巴属α - 辅肌动蛋白多肽的兔抗体与纯化蛋白样品和细胞提取物中的所有这些电泳变体发生反应。通过对固定阿米巴的间接荧光抗体染色，α - 辅肌动蛋白分布于整个细胞质基质中，并集中在皮层的透明细胞质中。该蛋白在有和没有Ca++的情况下都能交联肌动蛋白丝。它略微抑制肌动蛋白单体自发聚合的时间进程，但对肌动蛋白聚合的临界浓度没有影响，尽管它在一定程度上增加了表观伸长率。与其他一些交联蛋白一样，阿米巴α - 辅肌动蛋白抑制肌肉肌球蛋白亚片段 - 1的肌动蛋白激活的ATP酶。尽管棘阿米巴属α - 辅肌动蛋白在形状和交联肌动蛋白丝的能力方面类似于其他细胞的α - 辅肌动蛋白，但针对阿米巴和平滑肌α - 辅肌动蛋白的抗体不会发生交叉反应，并且在氨基酸组成和分子尺寸上存在显著差异。
