Identification of a large polypeptide precursor of avian oncornavirus proteins.

Antibody to partially disrupted avian myeloblastosis virus was used to selectively precipitate newly synthesized intracellular viral polypeptides from extracts of infected chicken cells. When analyzed by sodium dodecyl sulfate-gel electrophoresis, immune precipitates from extracts of cells pulse-labeled for 10 min with [(35)S]methionine contain none of the major virion polypeptides. Instead they show prominent viral specific polypeptides of molecular weight 76,000 and 12,000, as well as minor quantities of other labeled polypeptides. From pulse-chase kinetics and two-dimensional tryptic finger-prints it appears that the large polypeptide is a precursor of at least the two major virion proteins of molecular weights 24,000 and 11,000, while the smaller is a precursor of the 11,000-dalton virion protein.