Why POMC is considered as a multifunctional precursors?

Proopiomelanocortin (POMC) is a large protein (31,000 Daltons), which is isolated from both the pars distalis and the pars intermedia of the pituitary gland. This protein, POMC, contains sequences of corticotropin (adrenal cortical stimulating hormone, ACTH) and beta-LPH (beta-Lipotropic hormone). The first 13 amino acids of ACTH are identical to those of alpha-MSH. In the pars distalis ACTH is released under certain physiological conditions to regulate adrenocortical function. In the pars intermedia, on the other hand, enzymes are present within the secretory granules and are responsible for the enzymatic cleavage of POMC to alpha-MSH. Following cleavage from the precursor protein, post-translational amidation and acetylation of the C terminus and N terminus, respectively, of the MSH molecule then occurs. Thus, the precursor protein, POMC, contains within its primary structure the sequences of five MCs: alpha-MSH, beta-MSH, gamma-MSH, ACTH and beta-LPH, as well as several opiate peptides. Hence, it is considered as the multifunctional precursors.