STRUCTURE AND FUNCTION OF THE SV40 SMALL-T ANTIGEN

猴病毒40（SV 40）小t抗原增强病毒转化 效率，大概是通过其对细胞生长的影响报告 诱导 最近发现小t蛋白与细胞酶结合， 蛋白磷酸酶2A（PP 2A），降低其活性，提供了一个重要的 小T的行动线索 在拟议的实验中，我们将： (1)使用确定的点突变体来探测small-t和PP 2A的相互作用， 特别强调PP 2A抑制与 转化的增强， (2)确定与PP 2A相互作用所需的small-t序列， (3)定义小T的结构和金属结合在 保持结构完整性和PP 2A抑制作用， (4)分析感染细胞内关键蛋白的磷酸化状态， 细胞，特别是蛋白质，如Na+/H+-反向转运蛋白，大T抗原和 其他已知在生长促进中起作用的， (5)在酿酒酵母中表达小t，以确定这是否 影响酵母细胞周期进程，这是明确定义的遗传， 和 (6)研究small-t对细胞内pH控制的影响， 通过激活Na+/H+反向转运蛋白，可能通过 磷酸化，或激活替代的H+-排出途径。

The simian virus 40 (SV40) small-t antigen enhances viral transformation efficiency, presumably through its reported effects on cellular growth induction. The recent finding that small-t binds the cellular enzyme, protein phosphatase 2A (PP2A), reducing its activity, provides an important clue to the action of small-t. In the proposed experiments, we will: (1) use defined point mutants to probe the interaction of small-t and PP2A, with particular emphasis on the relationship between PP2A inhibition and the enhancement of transformation, (2) determine sequences of small-t required for interaction with PP2A, (3) define the structure of small-t and the role of metal binding in maintaining structural integrity and on PP2A inhibition, (4) analyze the phosphorylation state of key proteins within infected cells, notably proteins such as the Na+/H+-antiporter, large-T antigen and others known to play a role in growth promotion, (5) express small-t in Saccharomyces cerevesiae to determine whether this affects yeast cell cycle progression, which is well-defined genetically, and (6) study the effects of small-t on intracellular pH control which may result either by activation of the Na+/H+-antiporter, possibly through phosphorylation, or activation of an alternate H+-extrusion pathway.