Acts as essential component of the translation initiation factor 2B (eIF2-B or GCD complex), which catalyzes the exchange of eukaryotic initiation factor 2 (eIF-2)-bound GDP for GTP and is regulated by phosphorylated eIF-2. 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). Translation initiation factor 2B (eIF2-B) is composed of five different subunits; alpha (GCN3), beta (GCD7), gamma (GCD1), delta (GCD2) and epsilon (GCD6). A regulatory subcomplex comprising GCN3, GCD7 and GCD2 interacts preferentially with phosphorylated eIF-2 and has no exchange activity in vitro. Present with 10300 molecules/cell in log phase SD medium. Belongs to the eIF-2B alpha/beta/delta subunits family.