Cellular proteins reactive with monoclonal antibodies directed against simian virus 40 T-antigen.

Several recently isolated monoclonal antibodies which reacted with simian virus 40 T antigens also reacted with proteins found in uninfected and untransformed cells. The proteins were different from each other, PAb419 reacting with a 35,000-molecular-weight protein, PAb427 reacting with a 75,000-molecular-weight phosphoprotein, PAb405 reacting with a 150,000-molecular-weight phosphoprotein, and PAb204 reacting with a 68,000-molecular-weight protein. It is suggested that although some of these cross-reactions may be fortuitous, they may, as an alternative, reflect similarities of shape and perhaps function between domains of the viral T antigen and the relevant host proteins.