A translation repressor element resides in the 3' untranslated region of human p53 mRNA.

The 3' untranslated region of human p53 mRNA represses translation both in vitro and in vivo. Here, we identify a cis-acting 66-nucleotide U-rich sequence in the human p53 mRNA 3' untranslated region that mediates translational repression. Using UV cross-linking, we detect a 40 kDa protein that interacts specifically with the p53 3'UTR containing the repressor element. Enhanced translation of p53 mRNA contributes to the accumulation of p53 protein in cells exposed to gamma-radiation and could be a consequence of relieving the inhibition mediated by the repressor element.