ИСТИНА

Polyadenine binding protein (PABP) is ubiquitous one among eukaryotes. PABP binds poly-A tail of mRNA protecting it from degradation. Also, the protein interacts with initiator factor eIF4G thereby forming “close-loop” structure of mRNA during translation. Apart from these functions C-terminal domain of PABP interacts with PAM motives in the N domain of termination factor eRF3. This interaction was shown to reduce NMD level and stimulate termination on premature stop codons. We demonstrated stimulation of translation termination by human PABP using in vitro reconstituted system. Interplay of PABP and eRF3 promotes 2 nt shift of the ribosomal complex during termination in toe-print analysis consistent with stop codon recognition. Also we demonstrated that this interaction increases peptide release activity of eRF1. To determine whether RNA-binding activity is necessary we obtained truncated PABP mutant without four RNA-recognition motives. This mutant showed the same effects as full-length PABP.