Isolation of antibodies specific for avian viral and cellular myc proteins

The myc gene has been implicated in the genesis of various neoplasms in birds, mice, and humans and was originally identified as the cellular homologue of the transforming gene (v-myc) of the avian myelocytomatosis virus MC29. For specific antisera to be obtained for the myc gene product, a bacterial expression vector was constructed in which the coding sequences for approximately 20 kd of MC29 p110gag-myc (amino acid residues 502 to 678) were placed between the coding sequences for the amino terminal 13 kd of Rous sarcoma virus pp60src and the coding sequences for 112 kd of beta-galactosidase. Expression of this tripartite gene was driven by a hybrid trp-lac promoter under lac repressor control. Induction of expression resulted in the production of a 145-kd hybrid protein containing src, myc, and beta-galactosidase sequences. The hybrid protein was purified and injected into rabbits to produce antisera. The resultant antisera immunoprecipitated p110gag-myc and p58myc -p60myc from MC29- and MH2-infected nonproducer quail fibroblasts, respectively. In addition, the antisera also immunoprecipitated a 58-kd protein from the bursal lymphoma cell line BK25, which was identified as chicken c (cellular)-myc gene product.