InterPro domain: IPR009000

A beta barrel of circularly permuted topology is found in many transcription proteins, including initiation and elongation factors, and also some ribosomal proteins, although in these cases the fold is elaborated with additional structures. The beta barrel domain is represented by domain 2 of the elongation factors EF-Tu [ 1 ] and eEF1A [ 2 ], both of which function to recognise and transport aminoacyl-tRNA to the acceptor (A) site of the ribosome during the elongation process, and of EF-G [ 3 ], which functions in translocating the peptidyl tRNA from the A site to the peptidyl (P) site. This domain is also present in initiation factors, in domain 2 of eIF2 gamma subunit [ 4 ], and domains 2 and 4 of IF2/eIF5B [ 5 ], both of which function to transport the initiator methionyl-tRNA to the ribosome. This beta barrel domain may be involved in interactions with the switch 2 region to stabilise the relative orientations of the domains, which undergo functionally important conformational changes between GTP- and GDP-bound states.

1. High resolution crystal structure of bovine mitochondrial EF-Tu in complex with GDP. J. Mol. Biol. 297, 421-36
2. Structural basis for nucleotide exchange and competition with tRNA in the yeast elongation factor complex eEF1A:eEF1Balpha. Mol. Cell 6, 1261-6
3. Structure of a mutant EF-G reveals domain III and possibly the fusidic acid binding site. J. Mol. Biol. 303, 593-603
4. The large subunit of initiation factor aIF2 is a close structural homologue of elongation factors. EMBO J. 21, 1821-32
5. X-Ray structures of the universal translation initiation factor IF2/eIF5B: conformational changes on GDP and GTP binding. Cell 103, 781-92