Figure 1.

Schematic representation of the complex co-translational events accompanying synthesis and biogenesis of nascent polypeptide chains in pro- and eukaryotes. (A) Events accompanying nascent peptide growth inside the ribosomal tunnel: co-translational α-helix formation and co-translational peptide stalling occur in both pro- and eukaryotes. (B) Events accompanying nascent peptide growth and maturation in the immediate vicinity of the tunnel exit: co-translational N-terminal Met removal, co-translational N-terminal acetylation and co-translational binding to signal recognition particle (SRP) occur in both pro- and eukaryotes; co-translational binding to trigger factor (TF) and co-translational deformylation are specific to prokaryotes; co-translational binding to nascent associated complex (NAC), Ssbs and co-translational N-terminal myristoylation are specific for eukaryotes. (C) Events accompanying nascent peptide growth and maturation outside the ribosomal tunnel: co-translational folding and oligomerization, co-translational chaperone binding and co-translational signal peptide cleavage occur in both pro- and eukaryotes; co-translational N-glycosylation, co-translational peptide self-cleavage, co-translational ubiquitination and degradation are specific for eukaryotes.