Two different protein-protein interactions in oligomeric complexes of SV40 large T antigen with the cellular oncoprotein p53.

The simian virus 40 (SV40) large T antigen appears in monomers, dimers and various high molecular weight homo-oligomers. EDTA treatment of cell extracts from SV40-infected and -transformed cells leads to a dissociation of the high molecular weight oligomers which can be reconstituted by dialysis against an EDTA free buffer. Hetero-oligomers, composed of T antigen and the oncoprotein p53 become disassembled in the presence of EDTA into forms sedimenting minimally at 7S and maximally at 14S. These low molecular weight T-p53 complexes are resistant to EDTA treatment. Therefore, our results suggest at least two kinds of protein-protein interactions, an EDTA resistant linkage between large T antigen and p53 and an EDTA-sensitive ionic interaction between T antigen molecules in highly oligomeric complexes.