PROTEIN-SYNTHESIS DEPENDENT CYTOPLASMIC TRANSLOCATION OF P53 PROTEIN AFTER SERUM STIMULATION OF GROWTH-ARRESTED MCF-7 CELLS

p53 protein was localized in the cytoplasm of growing and in the nucle us of growth-arrested MCF-7 cells. While the absolute amount and rate of synthesis of p53 in growing and arrested cells were nearly the same , the protein in growing cells was phosphorylated to a greater extent than in arrested cells. The abilities of the cytoplasmic and nuclear p 53 proteins to bind to DNA sequences specific for p53 protein binding did not differ remarkably despite their differential phosphorylation l evels. Serum-induced translocation of the p53 protein from the nucleus to the cytoplasm, as well as DNA and protein synthesis, were inhibite d by cycloheximide. These results suggest that the DNA synthesis-assoc iated cytoplasmic translocation of p53 protein in response to serum st imulation depends on de novo protein synthesis and not on alteration o f the protein's ability to bind to specific DNA sequences. (C) 1993 Wi ley Liss, Inc.