Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
In response to amino acid starvation, the kinase GCN2 in yeast activates amino acid biosynthesis. Two recent studies (Maurin et al., 2005; Hao et al., 2005) reveal that GCN2 in the brain of mice restricts intake of diets lacking essential amino acids.