The v-rel oncogene product is complexed with cellular proteins including its proto-oncogene product and heat shock...

The oncogene product, pp59v-rel, of avian reticuloendotheliosis virus (REV-T) is complexed in the cytosol of REV-T transformed lymphoid cells with cellular proteins. Monoclonal antibodies and antisera directed against different regions of pp59v-rel coimmunoprecipitate five cellular proteins (p124, p115, p75, p70, and p40) in addition to pp59v-rel. Cellular proteins with the same apparent molecular mass also copurify with pp59v-rel during sequential Sephacryl S200 and immunoaffinity chromatography. Antisera directed against the most abundant cellular protein in the complex, pp40, coimmunoprecipitate pp59v-rel and several cellular proteins with the same apparent molecular mass. The 75-kDa protein in the pp59v-rel complex is the product of c-rel proto-oncogene and is weakly phosphorylated. In MSB-1 cells this protein is not detectably phosphorylated or associated with cellular proteins. The 70-kDa protein in the pp59v-rel containing cytosolic complex is the constitutive form of avian heat shock protein 70 (HSC70). The p70 protein coimmunoprecipitates and copurifies with pp59v-rel using antisera directed against pp59v-rel and coimmunoprecipitates with antisera specific for pp40. The p70 isolated from immune complexes containing pp59v-rel shares V8 protease fragments with HSC70.