Proopiomelanocortin

Pro-opiomelanocortin (POMC) is a precursor polypeptide with 241 amino acid residues. It is synthesised by corticotrope cells of the anterior pituitary gland, melanotrope cells of the intermediate lobe of the pituitary gland, about 3000 neurons in the arcuate nucleus of the hypothalamus, and  smaller populations of neurons in the dorsomedial hypothalamus and brainstem.

The large molecule of POMC is the source of several important biologically active substances. POMC can be cleaved enzymatically into the following peptides:
 * adrenocorticotrophic hormone (ACTH) and &beta;-LPH in the anterior pituitary gland
 * CLIP, &gamma;-LPH, &alpha;-MSH and &beta;-endorphin in the intermediate lobe
 * &gamma;-MSH
 * met-enkephalin
 * &beta;-MSH

Each of these peptides is packaged in large dense-core vesicles that are released from the cells by exocytosis in response to appropriate stimulation. &alpha;-MSH produced by neurons in the arcuate nucleus has important roles in the regulation of appetite and sexual behavior, while &alpha;-MSH secreted from the intermediate lobe of the pituitary regulates the production of melanin. ACTH is a peptide hormone that regulates the secretion of glucocorticoids from the adrenal cortex.

&beta;-endorphin and met-enkephalin are endogenous opioid peptides with widespread actions in the brain.

Proopiomelanocortin Проопиомеланокортин