Hájková L, Björkegren Sjögren C, Korenbaum E, Nordberg P, Karlsson R
Department of Zoological Cell Biology, WGI, Stockholm University, Sweden.
Exp Cell Res. 1997 Jul 10;234(1):66-77. doi: 10.1006/excr.1997.3607.
We are investigating structure-function relationships in profilin and actin by site-specific mutagenesis using a yeast, Saccharomyces cerevisiae, expression system to produce wild-type and mutant proteins. This paper shows that deleting proline 96 and threonine 97, which are located close to the major actin binding site on profilin, did not significantly alter the interaction between profilin and phosphatidylinositol 4,5-bisphosphate, nor did it affect the profilin:poly(L-proline) interaction. The mutant protein, however, had a lower capacity to bind to actin in vitro than wild-type profilin, though it showed a slightly increased profilin-enhanced nucleotide exchange on the actin. When microinjected into Swiss 3T3 mouse fibroblasts or porcine aortic endothelial cells, the mutant profilin did not change the organization of the microfilament system like the wild-type profilin did. This provides further evidence that profilin controls microfilament organization in the cell by interacting directly with actin.
我们正在利用酵母（酿酒酵母）表达系统通过位点特异性诱变研究肌动蛋白结合蛋白和肌动蛋白之间的结构-功能关系，以产生野生型和突变型蛋白。本文表明，缺失位于肌动蛋白结合蛋白主要肌动蛋白结合位点附近的脯氨酸96和苏氨酸97，不会显著改变肌动蛋白结合蛋白与磷脂酰肌醇4,5-二磷酸之间的相互作用，也不会影响肌动蛋白结合蛋白与聚（L-脯氨酸）的相互作用。然而，该突变蛋白在体外与肌动蛋白结合的能力低于野生型肌动蛋白结合蛋白，尽管它在肌动蛋白上显示出肌动蛋白结合蛋白增强的核苷酸交换略有增加。当显微注射到瑞士3T3小鼠成纤维细胞或猪主动脉内皮细胞中时，突变型肌动蛋白结合蛋白不会像野生型肌动蛋白结合蛋白那样改变微丝系统的组织。这进一步证明肌动蛋白结合蛋白通过直接与肌动蛋白相互作用来控制细胞中的微丝组织。
