InterPro domain: IPR044127

In eukaryotes and archaea, the e/aIF2 factor is involved in the initiation of protein biosynthesis. In its GTP bound form, e/aIF2 delivers methionylated initiator tRNA to the small subunit of the ribosome. After the pairing between the AUG initiation codon on mRNA and the CAU anticodon of the initiator tRNA, GTP is hydrolysed and e/aIF2:GDP is released from the ribosome. In eukaryotes, eIF2B acts as the guanine nucleotide exchange factor for eIF2. Archaea have no equivalent of eIF2B, and the exchange between GDP and GTP is thought to be spontaneous [ 1 ]. eIF2 is composed of three subunits, alpha, beta and gamma. The gamma subunit forms the core of the heterotrimer and confers both tRNA binding and GTP/GDP binding [ 2 ].

This entry represents the domain 2 of eIF2gamma (EIF2g) from eukaryota and archaea. It adopts a beta-barrel structure, and is involved in binding to both charged tRNA [ 2 ].

1. Structural switch of the gamma subunit in an archaeal aIF2 alpha gamma heterodimer. Structure 14, 119-28
2. Structural changes enable start codon recognition by the eukaryotic translation initiation complex. Cell 159, 597-607