Schwob E, Martin R P
Laboratoire de Biochimie, Centre National de la Recherche Scientifique, Strasbourg, France.
Nature. 1992 Jan 9;355(6356):179-82. doi: 10.1038/355179a0.
Actin, a major cytoskeletal component of all eukaryotic cells, is one of the most highly conserved proteins. It is involved in various cellular processes such as motility, cytoplasmic streaming, chromosome segregation and cytokinesis. The actin from the yeast Saccharomyces cerevisiae, encoded by the essential ACT1 gene, is 89% identical to mouse cytoplasmic actin and is involved in the organization and polarized growth of the cell surface. We report here the characterization of ACT2, a previously undescribed yeast split gene encoding a putative protein (391 amino acids, relative molecular mass (Mr) 44,073) that is 47% identical to yeast actin. The requirement of the ACT2 gene for vegetative growth of yeast cells and the existence of related genes in other eukaryotes indicate an important and conserved role for these actin-like proteins. Superimposition of the Act2 polypeptide onto the three-dimensional structure of known actins reveals that most of the divergence occurred in loops involved in actin polymerization, DNase I and myosin binding, leaving the core domain mainly unaffected. To our knowledge, the Act2 protein from S. cerevisiae is the first highly divergent actin molecule described. Structural and physiological data suggest that the Act2 protein might have an important role in cytoskeletal reorganization during the cell cycle.
肌动蛋白是所有真核细胞主要的细胞骨架成分之一，是最高度保守的蛋白质之一。它参与多种细胞过程，如运动、胞质环流、染色体分离和胞质分裂。酿酒酵母中的肌动蛋白由必需的ACT1基因编码，与小鼠细胞质肌动蛋白有89%的同源性，参与细胞表面的组织和极性生长。我们在此报告ACT2的特征，ACT2是一个先前未描述的酵母分裂基因，编码一种假定的蛋白质（391个氨基酸，相对分子质量（Mr）44,073），与酵母肌动蛋白有47%的同源性。ACT2基因对酵母细胞营养生长的需求以及其他真核生物中相关基因的存在表明这些肌动蛋白样蛋白具有重要且保守的作用。将Act2多肽叠加到已知肌动蛋白的三维结构上显示，大多数差异发生在参与肌动蛋白聚合、脱氧核糖核酸酶I和肌球蛋白结合的环中，而核心结构域基本未受影响。据我们所知，酿酒酵母的Act2蛋白是首个被描述的高度分化的肌动蛋白分子。结构和生理数据表明，Act2蛋白可能在细胞周期中的细胞骨架重组中发挥重要作用。
