Simian virus 40 tumor-specific proteins: subcellular distribution and metabolic stability in HeLa cells infected with nondefective adenovirus type 2-simian virus 40 hybrid viruses

Abstract

HeLa cells infected with adenovirus type 2 (Ad2) SV-40 hybrid viruses produce several SV-40-specific proteins. These include the previously reported 28,000-dalton protein of Ad2+ND1, the 42,000- and 56,000-dalton proteins of Ad2+ND2, the 56,000-dalton protein of Ad2+ND4 and the 42,000-dalton protein of Ad2+ND5. The list of SV-40-specific proteins induced by Ad2+ND4 is extended to include proteins of apparent MW of 28,000, 42,000, 60,000, 64,000, 72,000, 74,000 and a doublet of 95,000. Cell fractionation studies demonstrate that the SV-40-specific proteins are detectable in the nuclear, cytoplasmic and plasma membrane fractions. By pulse-chase and cell fractionation experiments, 3 classes of SV-40-specific proteins can be distinguished with regard to metabolic stability: unstable in the cytoplasmic but stable in the nuclear and plasma membrane fractions, stable in the nuclear, cytoplasmic and plasma membrane fractions, and unstable in all subcellular fractions. Immunoprecipitation of infected cell extracts demonstrates that most of the above proteins share antigenic determinants with proteins expressed in hamsters bearing SV-40-induced tumors. Only the 42,000-dalton protein of Ad2+ND5 is not immunoprecipitable.