Agouti signalling peptide

Agouti signalling peptide (ASP) is a protein that is encoded by the Agouti gene in humans. It is a paracrine signalling molecule that interacts with Melanocortin receptors to control the type of melanin being produced in melanocytes.

Function

ASP is primarily known for its role in the regulation of pigmentation. It acts as an antagonist to the Melanocortin 1 receptor (MC1R), which is found on the surface of melanocytes. When ASP binds to MC1R, it inhibits the production of eumelanin (black/brown pigment) and promotes the production of pheomelanin (yellow/red pigment). This results in a shift in the color of the hair or skin from dark to light.

In addition to its role in pigmentation, ASP also plays a role in the regulation of energy homeostasis. It has been found to increase food intake and decrease energy expenditure, leading to an increase in body weight. This is thought to be due to its ability to act as an antagonist to the Melanocortin 4 receptor (MC4R), which is involved in the regulation of food intake and energy expenditure.

Clinical significance

Mutations in the Agouti gene that result in overexpression of ASP have been associated with obesity in both humans and animals. This is thought to be due to the peptide's ability to increase food intake and decrease energy expenditure.

In addition, variations in the Agouti gene that affect the function of ASP have been associated with variations in skin and hair color in humans. For example, certain variants of the Agouti gene have been associated with red hair and fair skin in individuals of European descent.

See also

• Agouti gene
• Melanocortin 1 receptor
• Melanocortin 4 receptor
• Melanin
• Melanocyte