Two large glycoprotein fragments related to the NH2-terminal part of the adrenocorticotropin–β-lipotropin precursor are the end products of the maturation process in the rat pars intermedia

Abstract

Pulse and pulse–chase studies of the peptide hormones synthesized in the rat pars intermedia showed that during the maturation of pro-opiomelanocortin (the adrenocorticotropin-β-lipotropin (ACTH–β-LPH) precursor) the N-terminal portion of the precursor was released as a glycopeptide of relative mass of 17 000–19 000 and did not undergo further proteolytic cleavage. This peptide is therefore proposed to be the biologically active species related to the amino terminal fragment of pro-opiomelanocortin in the rat pars intermedia.