Montenarh M, Müller D
FEBS Lett. 1987 Sep 14;221(2):199-204. doi: 10.1016/0014-5793(87)80925-0.
SV40 large T antigen is phosphorylated at up to ten different amino acids clustered in an N-terminal and a C-terminal part of the polypeptide chain. The N-terminal phosphorylated residues include Ser 123 and Thr 124. We have analyzed the oligomerization, the complex formation with the cellular oncoprotein p53 and the DNA-binding properties of T antigen from two different SV40 transformed cell lines which have either an amino acid exchange at Ser 123 to Phe (W7) or Thr 124 to Ile (D29). In comparison to wild-type T antigen both mutant T antigens have a slightly reduced binding affinity for both binding sites, I and II, of SV40 DNA. Phosphorylation at both residues of T antigen is not essential for formation of the complex with p53. Only the phosphorylation at Thr 124 seems to be critical for the formation of high molecular mass oligomers. Our data support the hypothesis that the oligomerization of T antigen seems to be implicated in viral DNA replication.
猴病毒40大T抗原在多达十个不同的氨基酸位点发生磷酸化，这些位点集中在多肽链的N端和C端部分。N端磷酸化残基包括丝氨酸123和苏氨酸124。我们分析了来自两种不同的猴病毒40转化细胞系的T抗原的寡聚化、与细胞癌蛋白p53的复合物形成以及DNA结合特性，这两种细胞系中，一种在丝氨酸123处发生氨基酸置换为苯丙氨酸（W7），另一种在苏氨酸124处发生氨基酸置换为异亮氨酸（D29）。与野生型T抗原相比，两种突变型T抗原对猴病毒40 DNA的两个结合位点I和II的结合亲和力均略有降低。T抗原两个位点的磷酸化对于与p53形成复合物并非必需。似乎只有苏氨酸124的磷酸化对于高分子量寡聚物的形成至关重要。我们的数据支持这样一种假说，即T抗原的寡聚化似乎与病毒DNA复制有关。
