FIGURE 2.

β‐arrestin signalling pathway. Schematic elucidating the mechanism of gain‐of‐function induced by a mutation (yellow diamond) in the melanocortin 4‐receptor (MC4R). The mutation causes an increase in the cell‐surface expression of MC4R, possibly via reduced internalization or rapid recycling, causing increased cyclic adenosine monophosphate (cAMP) production, as well as increased production of protein kinase A (PKA) and cAMP‐regulated guanine nucleotide exchange factors (Epac). AC, adenylyl cyclase; GDP, guanosine diphosphate; GTP, guanosine triphosphate; MSH, melanocyte‐stimulating hormone;