Molecular evolution of proopiomelanocortin in fish

Proopiomelanocortin (POMC) is a common precursor protein for several hormonal peptides, such as adrenocorticotropin, beta-lipotropin, alpha-, beta-, gamma-melanotropins (MSHs), and beta-endorphin secreted from the pituitary gland of vertebrates. These POW products exhibit a variety of physiological functions, which are associated with stress response and environmental adaptation. Here, we discussed the molecular evolution of the POW gene on the basis of our studies in all taxonomic groups of fish. This gene has evolved by gene duplication, which increased the number of copies, and by internal gene duplication and deletion of the MSH domains that prompted the diversity of POMC as to the number of MSHs.