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. GCD1 stabilizes the interaction between eIF-2 and GCD6 and stimulates the catalytic activity in vitro. 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. Present with 9530 molecules/cell in log phase SD medium. Belongs to the eIF-2B gamma/epsilon subunits family.