Agouti however does not normally play a role in

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Unformatted text preview: play a role in regulating weight. Agouti is usually expressed only in the skin, and mice homozygous for null mutations of agouti, such as extreme nonagouti (ae), do not display abnormalities of weight regulation. Controllo del colore del mantello nel topo a Intermediate pituitary a-MSH Mc1r a-MSH Melanocyte Black pigment Yellow pigment Dermal papilla b An agouti-related gene involved in weight regulation Figure 2. The Agouti signaling pathway. (a) Melanocyte pigment production is regulated by agouti and -melanocyte stimulating hormone ( -MSH). The paracrine signaling molecule agouti is produced by dermal papillae in the skin. Agouti binds to, and inhibits signaling through, the melanocortin-1 receptor (Mc1r), a G protein-coupled receptor present on the surface of melanocytes in overlying hair follicles. The resulting decreased Mc1r signaling induces melanocytes to synthesize the yellow/red pigment, pheomelanin. In contrast, the endocrine signaling molecule -MSH, produced and secreted by the intermediate pituitary (pars intermedia), binds to Mc1r and activates signaling, and this increased Mc1r signaling stimulates follicular melanocytes to synthesize the black pigment, eumelanin. (b) The classic agouti coat color, which app...
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This document was uploaded on 04/02/2014.

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