Subchapter 16A – Adrenocorticotropic Hormone

ACTH, which contains 39 amino acid residues, is a peptide hormone secreted from corticotropes in the pars distalis in the pituitary. This peptide is generated from a precursor protein called proopiomelanocortin by posttranslational processing. Release of ACTH is primarily stimulated by corticotropin-releasing hormone produced in the hypothalamus. Representative functions of ACTH include glucocorticoid synthesis and secretion from the adrenal cortex. The function of ACTH is mediated by the melanocortin-2 receptor (MC2R), which is an ACTH-specific receptor. The MC receptor accessory protein is essential for trafficking MC2R to the cell surface for functional expression. In addition to its classical function in the adrenal cortex, ACTH is involved in a variety of functions via MC1R, MC3R, MC4R, and MC5R, as these receptors are distributed widely in the body.