Molecular interactions and initiation of protein synthesis

The initiation of protein synthesis requires the binding of a ribosome char ged with the initiator methionyl-tRNA to the AUG initiation codon of an mRN A. In eukaryotes, initiation proceeds in three essential steps: the formati on of the preinitiation complex, its recruitment to the mRNA and its migrat ion to the correct initiator AUG. This process depends on a number of molec ular interactions between the multiple initiation factors, the initiator Me t-tRNA, the 40S ribosomal subunit and the mRNA. Translation initiation is u nder tight cellular control, which will often involve a modification of the interactions between initiation factors. Numerous viruses manipulate these regulatory mechanisms to usurp the translational machinery.