Translation initiation factor eIF2B subunit delta

UniProtKB accession:  P12754

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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. 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 synthesis of GCN4 in yeast under amino acid starvation conditions by suppressing the inhibitory effects of multiple AUG codons present in the leader of GCN4 mRNA. It may promote either repression or activation of GCN4 expression depending on amino acid availability. GCD2 is also required for cell viability. Its function can partially be replaced by GCN3 under normal growth conditions in GCD2-defective mutants, under AA starvation conditions GCN3 is an antagonist (GCN4 translational activator).