Abstract
p30-related proteins were examined in three in vitro--passaged Gross virus--induced cell lines derived from mice congenic at the H-2 complex: BALB.K-gv-1 (H-2k) (BkGV1), which produces infectious, oncogenic virus, and BALB.B-gv-1 (H-2b) (BbGV1) and BALB/c-gv-1 (H-2d) (BdGV1), which stopped producing infectious virus early in their passage history. The producer BkGV1 line made p30 and its expected precursors. BbGV1 and BdGV1 cells had multiple changes in p30-related protein expression. BbGV1 cells (i) synthesized a truncated gag precursor polyprotein of ca. 47 kilodaltons, (ii) expressed fewer p30-related molecules per cell on their surface than BkGV1 cells, (iii) produced functional reverse transcriptase, and (iv) budded morphologically mature virions which were neither infectious nor oncogenic. BdGV1 cells (i) produced no p30 but expressed some high-molecular-weight proteins with p30 determinants, (ii) expressed fewer p30-related determinants on their surface than BbGV1 cells, and (iii) harbored immature intracisternal viral particles (type A) but did not exhibit budding virions.