A NOVEL SIGNALING MOLECULE, P130, FORMS STABLE COMPLEXES IN-VIVO WITHV-CRK AND V-SRC IN A TYROSINE PHOSPHORYLATION-DEPENDENT MANNER

p47(v-crk) (v-Crk), transforming gene product containing Src homology (SH)-2 and -3 domains, induces an elevated level of tyrosine phosphory lation of several cellular proteins. Among these proteins, a 125-135 k Da protein (p130) shows marked phosphorylation at tyrosines and tight association with v-Crk, suggesting a direct signal mediator of v-Crk. Here we report the molecular cloning of rat p130 by immunoaffinity pur ification. The p130 is a novel SH3-containing signaling molecule with a cluster of multiple putative SH2-binding motifs of v-Crk. Immunochem ical analyses revealed that p130 is highly phosphorylated at tyrosines during transformation by p60(v-src) (v-Src), as well as by v-Crk, for ming stable complexes with these oncoproteins. The p130 behaves as an extremely potent substrate of kinase activity included in the complexe s and it is a major v-Src-associated substrate of the Src kinase by pa rtial peptidase mapping. Subcellular fractionation demonstrated that t he cytoplasmic p130 could move to the membrane upon tyrosine phosphory lation. The p130 (designated Cas for Crk-associated substrate) is a co mmon cellular target of phosphorylation signal via v-Crk and v-Src onc oproteins, and its unique structure indicates the possible role of p13 0(Cas) in assembling signals from multiple SH2-containing molecules.