Simian virus 40-specific ribosome-binding proteins induced by a nondefective adenovirus 2-simian virus 40 hybrid

Abstract

The intracellular distribution of the 2 SV-40-specific proteins, with apparent MW of 56,000 and 42,000, detectable in human [oral carcinoma] KB cells infected by a nondefective adenovirus 2-SV-40 hybrid, Ad2+ND2, was studied. After a 20 min pulse of [35S]methionine, about 2/3 of the newly synthesized 56K protein and 1/3 of the 42K protein were localized on the plasma membrane. The remainder of each protein was in the cytoplasm, but the nuclear fraction was virtually free of either component. A significant portion of both proteins present in the cytoplasmic fraction was complexed to the 40S ribosomal subunits and was not removed by treatment with 0.5 M KCl. The portion that was free in the cytoplasm could bind preferentially and quantitatively to purified 40S ribosomes in vitro, indicating that these SV-40 proteins may act as translational control elements in cells.