PRCII, a representative of a new class of avian sarcoma viruses

The Poultry Research Center Virus II (PRC II) is a replication-defective avian sarcoma virus with envelope determinants of the A and B subgroups. In nonproducing cells transformed by PRCII the products of the replicative genes gag, pol, and env are not demonstrable, but a single polyprotein of Mr 105,000 (p105) can be detected. P105 contains peptides of the gag proteins p19 and p27 plus transformationspecific sequences. It does not contain peptides of gPr95env of Pr180gag-PoI (with the possible exception of one pol peptide). The transformation-specific sequences of p105 are distinct form those of p100 of avian carcinoma virus MH2, of p1 10 coded for by avian myelocytoma virus MC29, and of p75 or p40 of avian erythroblastosis virus AEV. They also show no resemblance to p60src of Rous sarcoma virus. P105 is phosphorylated on a tyrosine residue and has an associated Phosphokinase activity. P105 appears to be capable of autophosphorylation and of phosphorylating homologous immunoglobulin