Yoakim M, Hou W, Songyang Z, Liu Y, Cantley L, Schaffhausen B
Department of Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111.
Mol Cell Biol. 1994 Sep;14(9):5929-38. doi: 10.1128/mcb.14.9.5929-5938.1994.
Phosphatidylinositol 3-kinase is an important element in both normal and oncogenic signal transduction. Polyomavirus middle T antigen transforms cells in a manner depending on association of its tyrosine 315 phosphorylation site with Src homology 2 (SH2) domains on the p85 subunit of the phosphatidylinositol 3-kinase. Both nonselective and site-directed mutagenesis have been used to probe the interaction of middle T with the N-terminal SH2 domain of p85. Most of the 24 mutants obtained showed reduced middle T binding. However, mutations that showed increased binding were also found. Comparison of middle T binding to that of the platelet-derived growth factor receptor showed that some mutations altered the specificity of recognition by the SH2 domain. Mutations altering S-393, D-394, and P-395 were shown to affect the ability of the SH2 domain to select peptides from a degenerate phosphopeptide library. These results focus attention on the role of the EF loop in the SH2 domain in determining binding selectivity at the third position after the phosphotyrosine.
磷脂酰肌醇3激酶是正常和致癌信号转导中的重要元件。多瘤病毒中间T抗原以其酪氨酸315磷酸化位点与磷脂酰肌醇3激酶p85亚基上的Src同源2（SH2）结构域结合的方式转化细胞。非选择性和定点诱变都已用于探究中间T与p85的N端SH2结构域之间的相互作用。获得的24个突变体中的大多数显示中间T结合减少。然而，也发现了结合增加的突变。将中间T的结合与血小板衍生生长因子受体的结合进行比较表明，一些突变改变了SH2结构域识别的特异性。改变S-393、D-394和P-395的突变被证明会影响SH2结构域从简并磷酸肽文库中选择肽的能力。这些结果将注意力集中在SH2结构域中的EF环在确定磷酸酪氨酸后第三位的结合选择性中的作用上。
