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   03-AUG-2022, entry version 64.
DE   RecName: Full=Eukaryotic translation initiation factor 2 subunit gamma;
DE            Short=eIF-2-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 (eIF-2),
CC       involved in the early steps of protein synthesis. In the presence of
CC       GTP, eIF-2 forms a ternary complex with initiator tRNA Met-tRNAi and
CC       then recruits the 40S ribosomal complex and initiation factors eIF-1,
CC       eIF-1A and eIF-3 to form the 43S pre-initiation complex (43S PIC), a
CC       step that determines the rate of protein translation. The 43S PIC binds
CC       to mRNA and scans downstream to the initiation codon, where it forms a
CC       48S initiation complex by codon-anticodon base pairing. This leads to
CC       the displacement of eIF-1 to allow GTPase-activating protein (GAP) eIF-
CC       5-mediated hydrolysis of eIF2-bound GTP. Hydrolysis of GTP and release
CC       of Pi, which makes GTP hydrolysis irreversible, causes the release of
CC       the 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 (eIF-2) is a
CC       heterotrimeric G-protein 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   -!- 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   PRIDE; O36041; -.
DR   GO; GO:0005525; F:GTP binding; IEA:UniProtKB-KW.
DR   GO; GO:0003924; F:GTPase activity; IEA:InterPro.
DR   GO; GO:0003743; F:translation initiation factor activity; IEA:UniProtKB-KW.
DR   Gene3D; 3.40.50.300; -; 1.
DR   InterPro; IPR027417; P-loop_NTPase.
DR   InterPro; IPR000795; T_Tr_GTP-bd_dom.
DR   Pfam; PF00009; GTP_EFTU; 1.
DR   PRINTS; PR00315; ELONGATNFCT.
DR   SUPFAM; SSF52540; SSF52540; 1.
DR   PROSITE; PS51722; G_TR_2; 1.
PE   3: Inferred from homology;
KW   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