Host nuclear proteins expressed in simian virus 40-transformed and -infected cells.

Abstract

Two new families of host proteins (MW 48,000 [rat, mouse, human and hamster] and 55,000), in addition to the viral large (T) and small tumor antigens, are precipitable, with anti-T antiserum, from cells transformed on infected by the DNA tumor virus SV-40. Rabbit anti-mouse 48,000 protein antiserum reacts specifically with SV-40-infected or -transformed mouse cells to give nuclear staining indistinguishable from T-antigen staining but does not react with SV-40-transformed human cells which nevertheless have structurally analogous 48,000 proteins, nor does it give nuclear fluorescence with untransformed mouse cells. Comparison of the partial proteolytic digests of the 48,000 proteins from cultured cells of various mammalian species showes that they are structurally related but not related to the 55,000 or large T-antigen proteins. The 55,000 proteins from the various mammalian species were also structurally related.