Proopiomelanocortin
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| Proopiomelanocortin
| |
| Identifiers | |
| Symbol | POMC |
| Entrez | 5443 |
| HUGO | 9201 |
| OMIM | 176830 |
| RefSeq | NM_000939 |
| UniProt | P01189 |
| Other data | |
| Locus | Chr. 2 p23 |
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Pro-opiomelanocortin (POMC) is a precursor polypeptide with 241 amino acid residues.
Production
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
- smaller populations of neurons in the dorsomedial hypothalamus and brainstem
- melanocytes in the skin
Derivatives
The large molecule of POMC is the source of several important biologically active substances. POMC can be cleaved enzymatically into the following peptides:
- adrenocorticotropic hormone (ACTH) and β-LPH in the anterior pituitary gland
- CLIP, γ-LPH, α-MSH and β-endorphin in the intermediate lobe
Although the N-terminal 5 amino acids of beta-endorphin are identical to the sequence of Met-enkephalin, it is not generally thought that beta-endorphin is converted into Met-enkephalin. Instead, Met-enkephalin is produced from its own precursor, proenkephalin.
The production of beta-MSH occurs in humans but not in mice or rats due to the absence of the enzymatic processing site in the rodent POMC.
Functions
Each of these peptides is packaged in large dense-core vesicles that are released from the cells by exocytosis in response to appropriate stimulation.
- α-MSH produced by neurons in the arcuate nucleus has important roles in the regulation of appetite and sexual behavior, while α-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.
- β-endorphin and met-enkephalin are endogenous opioid peptides with widespread actions in the brain.
See also
External links
Peptides: neuropeptides | |
|---|---|
| Hypothalamic | Somatostatin - CRH - GnRH - GHRH - Orexins - TRH - POMC (ACTH, MSH, Lipotropin) |
| Gastrointestinal hormones | Cholecystokinin - Gastric inhibitory polypeptide - Gastrin - Motilin - Secretin - Vasoactive intestinal peptide |
| Other hormones | Vasopressin - Calcitonin - |
| Other | Angiotensin - Bombesin/Neuromedin B - Calcitonin gene-related peptide - Carnosine - Delta sleep-inducing peptide - FMRFamide - Galanin - Gastrin releasing peptide - Kinins (Bradykinin, Tachykinins ) - Neuromedin (B, N, U) - Neuropeptide Y - Neurophysins - Neurotensin - Opioid peptide - Pancreatic polypeptide - Pituitary adenylate cyclase activating peptide |
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
