n-terminal peptide of proopiomelanocortin n-terminal peptide of proopiomelanocortin the n-terminal peptide/fragment of proopiomelanocortin (npp; n-pomc), also known as pro-γ-msh, is a naturally occurring, endogenous metabolite of the polypeptide proopiomelanocortin (pomc). n-terminal peptide of proopiomelanocortinidentifierssymboln-pomcalt. symbolsnpp; pro-γ-msh n-pomc is also a precursor for γ1-msh, γ2-msh, and γ3-msh, and can form them through proteolytic cleavage. n-pomc is an adrenal growth factor.