ASIP encodes agoui, a signaling protein that is involved in regulating the production of melanin by acting as an inhibitor.
Involved in the regulation of melanogenesis. The binding of ASP to MC1R precludes alpha-MSH initiated signaling and thus blocks the production of cAMP, leading to a down-regulation of eumelanogenesis (brown/black pigment) and thus increasing the 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 lipid metabolism with adipocytes.
If you carry the G-allele in this gene, then you may be predisposed to unbalanced melanin production, leading to higher pheomelanin, which predisposes to a fair skin type and sensitive skin. This results in less protection for the skin against UV rays and sun exposure.