ИСТИНА

PABP (polyadenylate binding protein) activates translation termination. Interaction of PABP wth eRF3 underlies the function of PABP in this stage of translation. There are two main regulators of PABP in translation - PAIP1 and PAIP2. They interact with PABP via PAM1 and PAM2 motives. Additionally, PAIP1 contains MIF4G domain. PAIP1 is thought to stabilise closed-loop structure of mRNA that leads to stimulation of translation. On the contrary, PAIP2 inhibits translation, reducing concentration of PABP bound to eIF4G and poly(A)-tails. We found that PAIP2 competes with eRF3 for PABP binding that decreases activity of PABP in translation termination. Probably, it is an additional pathway of PABP suppression by PAIP2 during translation. PAIP1 was also found to compete with eRF3 for PABP binding, but only under specific conditions. Therefore, it is unlikely that PAIP1 can inhibit translation in vivo.