ID IF2G_SPIVO Reviewed; 210 AA.
AC O36041;
DT 15-JUL-1998, integrated into UniProtKB/Swiss-Prot.
DT 01-JAN-1998, sequence version 1.
DT 27-MAR-2024, entry version 69.
DE RecName: Full=Eukaryotic translation initiation factor 2 subunit gamma;
DE Short=eIF2-gamma;
DE EC=3.6.5.3;
DE Flags: Fragment;
OS Spironucleus vortens.
OC Eukaryota; Metamonada; Diplomonadida; Hexamitidae; Hexamitinae;
OC Spironucleus.
OX NCBI_TaxID=58336;
RN [1]
RP NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC STRAIN=ATCC 50386;
RX PubMed=9287422; DOI=10.1093/oxfordjournals.molbev.a025832;
RA Keeling P.J., Doolittle W.F.;
RT "Widespread and ancient distribution of a noncanonical genetic code in
RT diplomonads.";
RL Mol. Biol. Evol. 14:895-901(1997).
CC -!- FUNCTION: As a subunit of eukaryotic initiation factor 2 eIF2, involved
CC in the early steps of protein synthesis. In the presence of GTP, eIF-2
CC forms a ternary complex with initiator tRNA Met-tRNAi and then recruits
CC the 40S ribosomal complex and initiation factors eIF-1, eIF-1A and eIF-
CC 3 to form the 43S pre-initiation complex (43S PIC), a step that
CC determines the rate of protein translation. The 43S PIC binds to mRNA
CC and scans downstream to the initiation codon, where it forms a 48S
CC initiation complex by codon-anticodon base pairing. This leads to the
CC displacement of eIF-1 to allow GTPase-activating protein (GAP) eIF-5-
CC mediated hydrolysis of eIF2-bound GTP. Hydrolysis of GTP and release of
CC Pi, which makes GTP hydrolysis irreversible, causes the release of the
CC eIF-2-GDP binary complex from the 40S subunit, an event that is
CC essential for the subsequent joining of the 60S ribosomal subunit to
CC form an elongation-competent 80S ribosome. In order for eIF-2 to
CC recycle and catalyze another round of initiation, the GDP bound to eIF-
CC 2 must be exchanged with GTP by way of a reaction catalyzed by GDP-GTP
CC exchange factor (GEF) eIF-2B. {ECO:0000250|UniProtKB:P32481}.
CC -!- CATALYTIC ACTIVITY:
CC Reaction=GTP + H2O = GDP + H(+) + phosphate; Xref=Rhea:RHEA:19669,
CC ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:37565,
CC ChEBI:CHEBI:43474, ChEBI:CHEBI:58189; EC=3.6.5.3;
CC Evidence={ECO:0000250|UniProtKB:P32481};
CC -!- SUBUNIT: Eukaryotic translation initiation factor 2 eIF2 is a
CC heterotrimeric complex composed of an alpha, a beta and a gamma
CC subunit. The factors eIF-1, eIF-2, eIF-3, TIF5/eIF-5 and methionyl-
CC tRNAi form a multifactor complex (MFC) that may bind to the 40S
CC ribosome. {ECO:0000250|UniProtKB:P32481}.
CC -!- SUBCELLULAR LOCATION: Cytoplasm, cytosol
CC {ECO:0000250|UniProtKB:Q09130}.
CC -!- SIMILARITY: Belongs to the TRAFAC class translation factor GTPase
CC superfamily. Classic translation factor GTPase family. EIF2G subfamily.
CC {ECO:0000255|PROSITE-ProRule:PRU01059}.
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DR EMBL; U94408; AAB81022.1; -; Genomic_DNA.
DR AlphaFoldDB; O36041; -.
DR SMR; O36041; -.
DR GO; GO:0005829; C:cytosol; IEA:UniProtKB-SubCell.
DR GO; GO:0005850; C:eukaryotic translation initiation factor 2 complex; ISS:UniProtKB.
DR GO; GO:0005525; F:GTP binding; IEA:UniProtKB-KW.
DR GO; GO:0003924; F:GTPase activity; IEA:InterPro.
DR GO; GO:1990856; F:methionyl-initiator methionine tRNA binding; ISS:UniProtKB.
DR GO; GO:0003743; F:translation initiation factor activity; IEA:UniProtKB-KW.
DR GO; GO:0002183; P:cytoplasmic translational initiation; ISS:UniProtKB.
DR Gene3D; 3.40.50.300; P-loop containing nucleotide triphosphate hydrolases; 1.
DR InterPro; IPR027417; P-loop_NTPase.
DR InterPro; IPR000795; T_Tr_GTP-bd_dom.
DR PANTHER; PTHR42854; EUKARYOTIC TRANSLATION INITIATION FACTOR 2 SUBUNIT 3 FAMILY MEMBER; 1.
DR PANTHER; PTHR42854:SF3; EUKARYOTIC TRANSLATION INITIATION FACTOR 2 SUBUNIT 3-RELATED; 1.
DR Pfam; PF00009; GTP_EFTU; 1.
DR PRINTS; PR00315; ELONGATNFCT.
DR SUPFAM; SSF52540; P-loop containing nucleoside triphosphate hydrolases; 1.
DR PROSITE; PS51722; G_TR_2; 1.
PE 3: Inferred from homology;
KW Cytoplasm; GTP-binding; Hydrolase; Initiation factor; Nucleotide-binding;
KW Protein biosynthesis.
FT CHAIN <1..>210
FT /note="Eukaryotic translation initiation factor 2 subunit
FT gamma"
FT /id="PRO_0000137446"
FT DOMAIN <1..196
FT /note="tr-type G"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU01059"
FT REGION 2..9
FT /note="G1"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU01059"
FT REGION 30..34
FT /note="G2"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU01059"
FT REGION 85..88
FT /note="G3"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU01059"
FT REGION 141..144
FT /note="G4"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU01059"
FT REGION 174..176
FT /note="G5"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU01059"
FT BINDING 5..10
FT /ligand="GTP"
FT /ligand_id="ChEBI:CHEBI:37565"
FT /evidence="ECO:0000250|UniProtKB:P32481"
FT BINDING 141..144
FT /ligand="GTP"
FT /ligand_id="ChEBI:CHEBI:37565"
FT /evidence="ECO:0000250|UniProtKB:P32481"
FT BINDING 174..176
FT /ligand="GTP"
FT /ligand_id="ChEBI:CHEBI:37565"
FT /evidence="ECO:0000250|UniProtKB:P32481"
FT NON_TER 1
FT NON_TER 210
SQ SEQUENCE 210 AA; 23288 MW; E2CFE81CB04AF47E CRC64;
IGHVAHGKST LCKVLTGVDP IKFAAEKVNN ITIKLGFANA KIFECKDCAA PKNYFSQKSS
SPDQPPCPTC KGTHTQLLRH ISIIDCPGHH DYMTTMLSGV AAMDGTLLLI SAEQRCPQEQ
TREHFQAIQA TGQKKIIIAQ NKIDLVTEQQ AQNNYQEIQA FVHGISDINV VPISAIQNLN
IDYILKHLVE TITPPRRNLK AHPRFTIIRS
//
