Summary: Translation-initiation factor 2
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Translation-initiation factor 2 Provide feedback
IF-2 is a translation initiator in each of the three main phylogenetic domains (Eukaryotes  Bacteria  and Archaea ). IF2 interacts with formylmethionine-tRNA, GTP, IF1, IF3 and both ribosomal subunits . Through these interactions, IF2 promotes the binding of the initiator tRNA to the A site in the smaller ribosomal subunit and catalyses the hydrolysis of GTP following initiation-complex formation .
Aury JM, Jaillon O, Duret L, Noel B, Jubin C, Porcel BM, Segurens B, Daubin V, Anthouard V, Aiach N, Arnaiz O, Billaut A, Beisson J, Blanc I, Bouhouche K, Camara F, Duharcourt S, Guigo R, Gogendeau D, Katinka M, Keller AM, Kissmehl R, Klotz C, Koll F, Le , Nature. 2006;444:171-178.: Global trends of whole-genome duplications revealed by the ciliate Paramecium tetraurelia. PUBMED:17086204 EPMC:17086204
Hedegaard J, Hauge M, Fage-Larsen J, Mortensen KK, Kilian M, Sperling-Petersen HU, Poulsen K;, Microbiology. 2000;146:1661-1670.: Investigation of the translation-initiation factor IF2 gene, infB, as a tool to study the population structure of Streptococcus agalactiae. PUBMED:10878130 EPMC:10878130
Falb M, Pfeiffer F, Palm P, Rodewald K, Hickmann V, Tittor J, Oesterhelt D;, Genome Res. 2005;15:1336-1343.: Living with two extremes: conclusions from the genome sequence of Natronomonas pharaonis. PUBMED:16169924 EPMC:16169924
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR023115
Initiation factor 2 (IF-2) is one of the three factors required for the initiation of protein biosynthesis in bacteria. IF-2 promotes the GTP-dependent binding of the initiator tRNA to the small subunit of the ribosome. IF-2 is a protein of about 70 to 95 kDa that contains a central GTP-binding domain flanked by a highly variable N-terminal domain and a more conserved C-terminal domain. Some members of this group undergo protein self splicing that involves a post-translational excision of the intein followed by peptide ligation.
The function of IF-2 in facilitating the proper binding of initiator methionyl-tRNA to the ribosomal P site appears to be universally conserved, with an IF-2 homologue (aIF-2) present in archaea bacteria [PUBMED:10200264] Methanopyrus kandleri.
This entry represents the domain 3 of IF-2. It consists of a alpha/beta/alpha structure with a core formed by a parallel beta-sheet of 4 strands [PUBMED:11114334].
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Curation and family details
|Author:||Mistry J, Gavin OL|
|Number in seed:||243|
|Number in full:||5391|
|Average length of the domain:||108.80 aa|
|Average identity of full alignment:||42 %|
|Average coverage of the sequence by the domain:||13.02 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||3|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the IF-2 domain has been found. There are 6 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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