Specific interaction between the p53 cellular tumour antigen and major heat shock proteins.

The protein p53 is capable of participating in neoplastic transformation and can form specific complexes with the large-T antigen of simian virus 40 (SV40). This interaction probably results in the stabilization of p53 (refs 7,8) and may contribute to SV40-mediated transformation. Several non-SV40-transformed cells also exhibit a stabilized p53 which is present in elevated levels. Recently, this stabilization was shown to coincide with the ability to precipitate a polypeptide (p68) of relative molecular mass (Mr) 68,000-70,000 by anti-p53 monoclonal antibodies. We now report that this co-precipitation indeed represents a specific complex between the two proteins; the complex sediments on a sucrose gradient as a relatively broad peak of 10-14S and can be dissociated in vitro. Furthermore, p68 is the HSP70 heat shock protein cognate, found in elevated levels in a p53-overproducing cell line. On heat-shock treatment of such overproducers, p53 also forms a complex with the related highly inducible HSP68.