Agouti and Agouti-related Protein: Analogies and Contrasts

The document reviewed the roles of the agouti gene and agouti-related protein (AGRP) in mammalian pigmentation and obesity. The agouti gene, initially studied in mice, influenced pigmentation and was linked to obesity and diabetes through its antagonistic effects on melanocortin receptors MC1-R and MC4-R. Overexpression of agouti led to the A^y phenotype, characterized by yellow fur and obesity. AGRP, discovered in 1997, shared structural similarities with agouti but primarily affected central melanocortin receptors MC3-R and MC4-R, influencing feeding behavior and energy homeostasis. The review highlighted the complex genetic regulation and broader signaling roles of agouti and AGRP beyond pigmentation, with implications for understanding metabolic disorders.