Roles of acetylation and other post-translational modifications in melanocortin function and interactions with endorphins.

Phylogenetic, developmental, anatomic, and stimulus-specific variations in post-translational processing of POMC are well established. For melanocortins, the role of alpha-N-acetylation and the selective activities of alpha, beta, and gamma forms are of special interest. Acetylation may shift the predominant activity of POMC products between endorphinergic and melanocortinergic actions-which are often in opposition. This review addresses: (1) variations in POMC processing; (2) the influence of acetylation on the functional activity of alpha-MSH; (3) state- and stimulus-dependent effects on the proportional distribution of forms of melanocortins and endorphins; (4) divergent effects of alpha-MSH and beta-endorphin administration; (5) potential roles of beta- and gamma-MSH.