Acts as a catalytic 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. GCD6 and GCD7 repress GCN4 expression at the translational level by ensuring that ribosomes which have translated UORF1 will reinitiate at UORF2, -3, or -4 and thus fail to reach the GCN4 start site. Translation initiation factor 2B (eIF2-B) is composed of five different subunits; alpha (GCN3), beta (GCD7), gamma (GCD1), delta (GCD2) and epsilon (GCD6). A catalytic subcomplex comprising GCD1 and GCD6 interacts with both, phosphorylated and non-phosphorylated eIF-2 and has exchange activity in vitro. GCD6 interacts with SUI3. Present with 33800 molecules/cell in log phase SD medium. Belongs to the eIF-2B gamma/epsilon subunits family.