Monoclonal antibodies displaying a novel species specificity for the primate transformation‐related protein, p53.

SV40 large T antigen associates with a cellular phosphoprotein, p53, in virus‐transformed cells. We have raised three new monoclonal antibodies, PAb1101, PAb1102 and PAb1103, to this cellular protein, derived from SV40‐transformed human fibroblasts. These define at least two non‐overlapping determinants on human p53 that are in different areas of the molecule from those recognised by previously available antibodies. Unlike those antibodies, PAb1102 and PAb1103 do not react with rodent p53. PAb1101 reacts far more weakly with rodent p53 than with primate p53. All three antibodies show a preference for binding to the large T‐associated form of p53, an effect that is particularly marked with PAb1102. The novel specificity of these antibodies allows further probing of the nature and function of the large T/p53 complex in human cells.