STRUCTURE AND FUNCTION OF THE SV40 SMALL-T ANTIGEN

猴病毒40(SV40)小T抗原促进病毒转化 效率，可能是通过报道其对细胞生长的影响 归纳法。最近的研究发现，Small-T结合了细胞酶， 蛋白磷酸酶2A(PP2A)，降低其活性，提供了重要的 关于Small-T行动的线索。在建议的试验计划中，我们会： (1)利用定点突变体探索Small-t与PP2A的相互作用， 特别强调了PP2A抑制与细胞周期调控的关系 加强转型， (2)确定与PP2A相互作用所需的小T序列， (3)确定了Small-T的结构和金属结合在其中的作用 保持结构完整性和抑制PP2A， (4)分析感染体内关键蛋白的磷酸化状态。 细胞，特别是Na+/H+逆向转运蛋白、大T抗原和 其他已知在促进增长方面发挥作用的人， (5)在酿酒酵母中表达Small-T 影响酵母细胞周期进程，这在基因上有很好的定义， 和 (6)研究Small-t对细胞内pH控制的影响，这可能是 结果可能是通过激活Na+/H+-逆向转运蛋白，可能是通过 磷酸化，或激活另一条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.