Fig 2: Effect of PDCD4 on TC2formationin the presence/absence of PABP.A, translation termination steps. Addition of GDPCP to the translation system stabilizes ribosome position according to TC1 +2 nt, addition of the eRF1(AGQ) stabilizes ribosome position according to TC2 +2 nt. B, TC formation analysis according to efficiency of ribosomal shift during stop-codon recognition in the presence/absence of PDCD4 and PABP on MVHL mRNA or MVHL-polyA mRNA. The background was subtracted and each mean value was normalized to the value of eRF1(AGQ)+eRF3a. The black dots show the replicate values. The error bars represent the standard error. ∗∗p < 0.01, t test, ∗p < 0.05, t test.

Fig 3: Model for eIF3j-stimulated translation termination. (A) Translation termination on the long CDS. (I) eIF3j binds to the preTC before release factors; (II) the eRF1-eRF3a-GTP-PABP complex binds to eIF3j to the A-site of the preTC; (III) after the stop codon recognition, GTP hydrolysis, and peptide release, eIF3j dissociates from eRF3-GDP. (B) Translation termination on the uORFs. (I) eIF3j binds to the preTC and possibly to eIF3; (II) the eRF1-eRF3a-GTP complex binds to eIF3j to the A-site of the preTC; (III) after the stop codon recognition, GTP hydrolysis, and peptide release, eIF3j dissociates from eRF3-GDP and remains associated with eIF3 on the 40S subunit.

Fig 4: eIF3j isoforms and mutants activity in peptide release. (A) Schematic representation of the eIF3j mutants used in this study. (B) Peptide release on the preTC(NL) induced by the addition of eRF1 and eRF3a in the presence of eIF3j, eIF3j isoforms, or eIF3j mutants (n = 3). The error bars represent the standard deviation; RLU, Relative Luminescence Units. (C) Motifs of eIF3j important for peptide release represented on the structure of eIF3j ((27); PDB 6YBW chain z, lacking 43 residues at the N-terminus, 23 residues at the C-terminus, and residues (97–112) and (136–152)).

Fig 5: PreTC NL binding with PDCD4 and the release factors. Western blot analysis of SDG fractions. preTC NL binding with PDCD4, eRF1(AGQ), and eRF3a; the fractions of sucrose gradient corresponding to ribosome complexes are highlighted in black.