Protein-protein interactions required during translation.

Protein synthesis requires the involvement of numerous accessory factors that assist the ribosome in translation initiation, elongation, and termination. Extensive protein-protein and protein-RNA interactions are required to bring together the accessory factors, tRNAs, ribosomes, and mRNA into a productive complex and these interactions undergo dynamic alterations during each step of the translation initiation process. Initiation represents the most complex aspect of translation, requiring more accessory proteins, called initiation factors, than either elongation or termination. Not surprisingly, initiation is most often the rate-limiting step of translation and, as such, most (but not all) examples of translational regulation involve the regulation of protein-protein or protein-RNA interactions of the initiation complex. In this review, we focus on those interactions required for efficient translation initiation and how such interactions are regulated by developmental or environmental signals.