A NEW 42-KDA PROTEIN-BINDING TO THE GROWTH SUPPRESSOR PROTEIN-P53

Expression of the growth suppressor gene p53 in Schizosaccharomyces po mbe causes growth arrest which can be suppressed by overexpression of a yeast gene termed tms1. The tms1 gene encodes a 37 KDa protein which binds to p53 in vitro and in vivo when p53 was expressed in fission y east cells. By using antibodies against recombinant tms1 protein we an alyzed mammalian cells for the expression of a tms1 related protein. H uman, monkey and rat cells exhibited a bright nuclear fluorescence whe n incubated with the tms1 specific antibody. In addition, we were able to specifically immunoprecipitate a 42 KDa protein which forms comple xes with the p53 protein. The specificity of these complexes was demon strated by coimmunoprecipitation using different monoclonal antibodies against p53, antibodies against yeast tms1 as well as by Western blot analysis. Thus, we found that the mammalian tms1 related protein repr esents a new p53 binding protein.