Figure 2.

p53 interacts with the 5′UTR of some mRNAs to inhibit their translation. Direct interaction between p53 and 5′UTR of different cellular mRNAs has been identified using in vitro approaches, the p53: RNA interaction occurring in regions known to form IRES (Internal Ribosome Entry Sites). Binding of p53 on 5′UTR has been shown to inhibit translation of the related mRNAs although the molecular mechanism remains to be clarified (dotted box). It can either result from inhibition of 80S ribosome formation, presence of p53 into polysome or p53-dependent RNA:RNA annealing to favor formation of particular mRNA structures such as IRES. (AAAAA) n: poly-A tail protecting mRNA against degradation; CAP: chemical modification of 5′ mRNA end involved in binding to canonical translation factors; CDS: coding sequence of mRNA; 5′UTR: 5′-UnTranslated Region; 40S: small ribosome subunit; 60S: large ribosome subunit; blue circle: p53 protein; orange dots: amino acids of neo-synthetized proteins.