Cells transformed by avian myelocytomatosis virus strain CMII contain a 90K gag-related protein

Abstract

Nonproducer clines of chicken bone marrow cells and quail embryo cells transformed by avian myelocytomatosis virus strain CMII were isolated. Analysis of [ 35S]methionine-labeled cell extracts of the nonproducer clones by immune precipitation showed that none of the three viral structural protein precursors, Pr 76 gag , gPr95 env , and Pr180 gag-pol were synthesized, but instead a 90,000 molecular weight protein (CMII-90K) were isolated. By using specific antisera this protein was shown to be related to the gag gene product, but not to the products of the pol or env genes. Competition radioimmunoassays showed that non-producer cells expressed inhibitory activity for p19 but not for p27 or p15. Tryptic peptide analysis of CMII-90K, Pr76 gag , gPr95 env , and the β-subunit of the viral reverse transcriptase confirmed the immunological data that the CMII-90K protein was shown to contain the p19 truptic peptides plus peptide which were specific for CMII and not related to env or pol gene products. The possible role of the CMII-90K protein in cell transformation is discussed.