Identification of Domains of the v-crk Oncogene Product Sufficient for Association with Phosphotyrosine-Containing Proteins

Abstract

The oncogene product of the avian sarcoma virus CT10, P47^gag-crk, contains the SH2, SH2', and SH3 domains and binds proteins in a phosphotyrosine (ptyr)-dependent manner. In this study, we have determined the region of P47^gag-crk essential for binding to ptyr-containing proteins. Mutant P47^gag-crk proteins expressed in Escherichia coli that have the intact SH2 and SH2' regions retained the capacity to bind ptyr-containing proteins obtained from cells transformed by crk and src. The deletion of SH2 resulted in the loss of binding activity. Other mutants that have altered SH2 or SH2' bound few, if any, of the ptyr-containing proteins. Those mutants that bound ptyr-containing proteins associated with tyrosine kinase activity. We also found that polypeptides containing SH2, SH2', and SH3 of p60^v-src and p60^c-src associated with ptyr-containing proteins from crk-transformed cells. Thus, the SH2 and SH2' domains of P47^gag-crk are responsible for their binding to ptyr-containing proteins.