UniProt functional annotation for P32481



	UniProt functional annotation for P32481

UniProt code: P32481.

Organism: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast).

Taxonomy: Eukaryota; Fungi; Dikarya; Ascomycota; Saccharomycotina; Saccharomycetes; Saccharomycetales; Saccharomycetaceae; Saccharomyces.

Function: As a subunit of eukaryotic initiation factor 2 (eIF-2), involved in the early steps of protein synthesis. In the presence of GTP, eIF-2 forms a ternary complex with initiator tRNA Met-tRNAi and then recruits the 40S ribosomal complex and initiation factors eIF-1, eIF-1A and eIF-3 to form the 43S pre-initiation complex (43S PIC), a step that determines the rate of protein translation. The 43S PIC binds to mRNA and scans downstream to the initiation codon, where it forms a 48S initiation complex by codon-anticodon base pairing. This leads to the displacement of eIF-1 to allow GTPase-activating protein (GAP) eIF- 5-mediated hydrolysis of eIF2-bound GTP. Hydrolysis of GTP and release of Pi, which makes GTP hydrolysis irreversible, causes the release of the eIF-2-GDP binary complex from the 40S subunit, an event that is essential for the subsequent joining of the 60S ribosomal subunit to form an elongation-competent 80S ribosome. In order for eIF-2 to recycle and catalyze another round of initiation, the GDP bound to eIF- 2 must be exchanged with GTP by way of a reaction catalyzed by GDP-GTP exchange factor (GEF) eIF-2B. {ECO:0000269|PubMed:11042214, ECO:0000269|PubMed:14698289, ECO:0000269|PubMed:16246727, ECO:0000269|PubMed:3888989, ECO:0000269|PubMed:3888990, ECO:0000269|PubMed:8947054, ECO:0000269|PubMed:9308967}.

Catalytic activity: Reaction=GTP + H2O = GDP + H(+) + phosphate; Xref=Rhea:RHEA:19669, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:37565, ChEBI:CHEBI:43474, ChEBI:CHEBI:58189; EC=3.6.5.3; Evidence={ECO:0000269|PubMed:3888990};

Subunit: Eukaryotic translation initiation factor 2 (eIF-2) is a heterotrimeric G-protein composed of an alpha, a beta and a gamma subunit. The factors eIF-1, eIF-1A, eIF-2, eIF-3, TIF5/eIF-5 and methionyl-tRNAi form a multifactor complex (MFC) that may bind to the 40S ribosome. {ECO:0000269|PubMed:11018020, ECO:0000269|PubMed:16522633}.

Miscellaneous: Present with 20800 molecules/cell in log phase SD medium. {ECO:0000269|PubMed:14562106}.

Similarity: Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family. EIF2G subfamily. {ECO:0000255|PROSITE-ProRule:PRU01059}.

Annotations taken from UniProtKB at the EBI.


Organism:		Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast).
Taxonomy:		Eukaryota; Fungi; Dikarya; Ascomycota; Saccharomycotina; Saccharomycetes; Saccharomycetales; Saccharomycetaceae; Saccharomyces.



Function:		As a subunit of eukaryotic initiation factor 2 (eIF-2), involved in the early steps of protein synthesis. In the presence of GTP, eIF-2 forms a ternary complex with initiator tRNA Met-tRNAi and then recruits the 40S ribosomal complex and initiation factors eIF-1, eIF-1A and eIF-3 to form the 43S pre-initiation complex (43S PIC), a step that determines the rate of protein translation. The 43S PIC binds to mRNA and scans downstream to the initiation codon, where it forms a 48S initiation complex by codon-anticodon base pairing. This leads to the displacement of eIF-1 to allow GTPase-activating protein (GAP) eIF- 5-mediated hydrolysis of eIF2-bound GTP. Hydrolysis of GTP and release of Pi, which makes GTP hydrolysis irreversible, causes the release of the eIF-2-GDP binary complex from the 40S subunit, an event that is essential for the subsequent joining of the 60S ribosomal subunit to form an elongation-competent 80S ribosome. In order for eIF-2 to recycle and catalyze another round of initiation, the GDP bound to eIF- 2 must be exchanged with GTP by way of a reaction catalyzed by GDP-GTP exchange factor (GEF) eIF-2B. {ECO:0000269\|PubMed:11042214, ECO:0000269\|PubMed:14698289, ECO:0000269\|PubMed:16246727, ECO:0000269\|PubMed:3888989, ECO:0000269\|PubMed:3888990, ECO:0000269\|PubMed:8947054, ECO:0000269\|PubMed:9308967}.


Catalytic activity:		Reaction=GTP + H2O = GDP + H(+) + phosphate; Xref=Rhea:RHEA:19669, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:37565, ChEBI:CHEBI:43474, ChEBI:CHEBI:58189; EC=3.6.5.3; Evidence={ECO:0000269\|PubMed:3888990};
Subunit:		Eukaryotic translation initiation factor 2 (eIF-2) is a heterotrimeric G-protein composed of an alpha, a beta and a gamma subunit. The factors eIF-1, eIF-1A, eIF-2, eIF-3, TIF5/eIF-5 and methionyl-tRNAi form a multifactor complex (MFC) that may bind to the 40S ribosome. {ECO:0000269\|PubMed:11018020, ECO:0000269\|PubMed:16522633}.
Miscellaneous:		Present with 20800 molecules/cell in log phase SD medium. {ECO:0000269\|PubMed:14562106}.
Similarity:		Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family. EIF2G subfamily. {ECO:0000255\|PROSITE-ProRule:PRU01059}.