The synthesis of new proteins is a highly regulated process that allows rapid cellular responses to diverse stimuli at the post-transcriptional level. Nine key eukaryotic translation initiation factors (eIFs) catalyze the assembly of a functional ribosomal complex in two steps - first, the formation of the 48S complex from the 43S initiation complex and mRNA followed by its subsequent joining with the 60S subunit, enabling polypeptide chain formation. Of the many steps in translation, the rate-limiting step, initiation, is subjected to the most regulatory control. Many stimuli, such as growth factors and stress, either stimulate or inhibit specific eIFs. Aside from initiation, translation can also be attenuated during elongation. For instance, elevated levels of Ca2+ or cAMP can block the action of eukaryotic elongation factor 2 (eEF2) via AMPK. Finally, upon recognition of a stop codon, eRF1 and eRF3 mediate termination of translation and ribosome disassembly and recycling
We would like to thank Rachel Wolfson and Prof. David Sabatini, Whitehead Institute for Biomedical Research, MIT, Cambridge, MA, for reviewing this diagram.
created January 2002
revised June 2014