The GCN (General Control Nonderepressible) is a group of proteins that are critically involved in the cellular signaling response to nutrient availability, particularly in activating protein synthesis during amino acid deprivation. Members of the GCN family include GCN2, GCN3, GCN4, among others, which have conserved functions across various organisms, including yeast and mammals. GCN2 is activated by sensing changes in amino acid levels, which then leads to a reduction in the overall rate of protein synthesis by phosphorylating eIF2α, while simultaneously specifically increasing the translation of certain response genes (such as GCN4). The expression and activity regulation of GCN proteins are crucial for cell adaptation to environmental changes. Specific expression and mutations in these genes can affect the cellular response to nutritional stress.