Translation initiation factor eIF2B subunit alpha

UniProtKB accession:  P14741

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UniProtKB description:  Acts as a component of the translation initiation factor 2B (eIF2B) complex, which catalyzes the exchange of GDP for GTP on the eukaryotic initiation factor 2 (eIF2) complex gamma subunit (PubMed:8506384, PubMed:9472020). Its guanine nucleotide exchange factor activity is repressed when bound to eIF2 complex phosphorylated on the alpha subunit, thereby limiting the amount of methionyl-initiator methionine tRNA available to the ribosome and consequently global translation is repressed (By similarity). It activates the translation of GCN4 in response to low amino acid, carbon, or purine availability, by suppressing the inhibitory effects of multiple uORFs present in the leader of GCN4 mRNA (PubMed:10733573). It may promote either repression or activation of GCN4 expression depending on amino acid availability (PubMed:8506384). Modulation of GCN3 regulatory function in response to amino acid availability occurs post-translationally (PubMed:8506384, PubMed:9472020).