Ras GTPase-activating protein-associated p62 is a major v-Src-SH3-binding protein

Oncogenic transformation by v-Src is accompanied by marked morphological changes and cytoskeletal reorganization, Yet, the cytoskeleton-associated proteins with which v-Src interacts are largely unknown, We have studied the binding of v-Src-SH3 domain to cellular proteins utilizing a blot overlay procedure with a GST-v-Src-SH3 fusion protein as probe, A major 62-64 kDa v-Src-SH3-binding protein, present in detergent-insoluble cellular fractions, was identified as p21(ras)-GTPase-activating protein-associated p62 (GAPA62), In non-transformed cells, including NIH 3T3 cells, GAPA62 was present in both the RIPA-soluble and RIPA-insoluble fractions, but only the latter form was tyrosine-phosphorylated. In contrast, in polyoma middle T antigen-transformed 3T3 cells, GAPA62 was present only in the RIPA-insoluble fraction, where it was highly phosphorylated, It is suggested that tyrosine phosphorylation of GAPA62 may be an important determinant of its cellular localization and its possible function as a mediator of v-Src actions. (C) 1997 Federation of European Biochemical Societies.