Melanocortin-Receptors are playing an important role in the maintenance of energy homeostasis. Alpha-MSH a Melanocortin-Receptor agonist induces arrestin-mediated Endocytosis of the Melanocortin-3-Receptor (MC3R). Similar effects have already been shown for the Melanocortin-4-Receptor (MC4R). Agouti-related-Protein the natural inverse agonist of MCR also induces arrestin-mediated endocytosis of MC3R and MC4R. The MC4R mutant D90N which has lost the ability of G-Protein-Activation recruits beta-arrestin after agonist-stimulation but does not show endocytosis.
