Agouti (ASIP) Protein

In mice, the agouti gene encodes a paracrine signaling molecule that causes hair follicle melanocytes to synthesize pheomelanin, a yellow pigment, instead of the black or brown pigment, eumelanin. Pleiotropic effects of constitutive expression of the mouse gene include adult-onset obesity, increased tumor susceptibility, and premature infertility. This gene is highly similar to the mouse gene and encodes a secreted protein that may (1) affect the quality of hair pigmentation, (2) act as a pharmacological antagonist of alpha-melanocyte-stimulating hormone, (3) play a role in neuroendocrine aspects of melanocortin action, and (4) have a functional role in regulating lipid metabolism in adipocytes. [provided by RefSeq, Jul 2008]

ASIP: Involved in the regulation of melanogenesis. The binding of ASP to MC1R precludes alpha-MSH initiated signaling and thus blocks production of cAMP, leading to a down-regulation of eumelanogenesis (brown/black pigment) and thus increasing synthesis of pheomelanin (yellow/red pigment). In higher primates, agouti may affect the quality of hair pigmentation rather than its pattern of deposition. Could well play a role in neuroendocrine aspects of melanocortin action. May have some functional role in regulating the lipid metabolism with adipocytes.

Protein type: Secreted; Secreted, signal peptide

Chromosomal Location of Human Ortholog: 20q11.2-q12

Cellular Component: extracellular space

Molecular Function: type 3 melanocortin receptor binding; type 4 melanocortin receptor binding; receptor binding

Biological Process: melanin biosynthetic process; generation of precursor metabolites and energy; regulation of molecular function, epigenetic; hormone-mediated signaling; cell-cell signaling; melanosome organization and biogenesis; adult feeding behavior; signal transduction; melanosome transport

Disease: Skin/hair/eye Pigmentation, Variation In, 9