Attractin' more attention - new pieces in the obesity puzzle?

Genetic, biochemical and pharmacological studies in humans and rodents have established that signalling through the G-protein-coupled melanocortin-4 receptor (MC4R) by pro-opiomelanocortin (POMC)-derived ligands plays a critical role in the central suppression of appetite. As a consequence, malfunction of this signalling system leads to the development of obesity. It has been shown previously that melanocortin signalling can be modulated by the type 1 transmembrane protein attractin, apparently acting as a co-receptor for the inhibitory ligand agouti. Work reported in this issue of Biochemical Journal (Haqq et al.) demonstrates that the cytosolic tail of an attractin-like protein (ALP) binds directly and specifically to the C-terminal region of MC4R, raising the possibility that proteins of the attractin family influence melanocortin receptor function through multiple mechanisms.