Translation process

Initiation

• Initiator met-tRNA, eukaryotic IF2 (eIF2), and GTP bind to the small ribosomal subunit to form a preinitiation complex (initially a 43s preinitiation complex).
  • eIF2: a small G protein
    • Binds initiator met-tRNA (ternary complex) and forms the final initiation complex by hydrolyzing GTP to GDP
    • Reconverted to the GTP-bound form by the guanine nucleotide exchange factor eIF2B

Elongation

• An aminoacyl-tRNA complex with eukaryotic elongation factor 1 (eEF1) hydrolyzes GTP, thereby releasing eEF1 and GDP and providing the energy for aminoacyl-tRNA to bind the A site (anticodon matches the codon of the mRNA).

Termination

• A release factor recognizes the stop codon, halts translation, and hydrolytically cleaves the peptidyl tRNA bonds (requires GTP), leading to release of the protein.