Agouti-signaling protein

Agouti-signaling protein (ASP) is a protein that in humans is encoded by the AGOUTI gene. The agouti-signaling protein is involved in the regulation of melanogenesis, the process responsible for pigmentation in the skin, hair, and eyes.

Function

The agouti-signaling protein acts as an antagonist to melanocortin receptors (specifically, MC1R and MC4R). It competes with alpha-melanocyte-stimulating hormone (α-MSH) for binding to these receptors. When ASP binds to MC1R in the skin, it inhibits the production of dark eumelanin pigments, leading to a lighter skin color.

In addition to its role in pigmentation, ASP is also involved in the regulation of body weight. It is expressed in the brain where it can bind to MC4R, a receptor involved in the regulation of food intake and energy expenditure.

Clinical significance

Mutations in the AGOUTI gene can lead to a variety of conditions. For example, the overexpression of ASP has been associated with obesity in mice. In humans, certain variants of the AGOUTI gene have been linked to an increased risk of obesity and type 2 diabetes.

See also

• Melanocortin receptor
• Alpha-melanocyte-stimulating hormone
• Obesity
• Type 2 diabetes