Corticotropin
| pro-opiomelanocortin | |
|---|---|
| Identifiers | |
| Symbol | OMC |
| Entrez | 5443 |
| HUGO | 9201 |
| OMIM | 176830 |
| RefSeq | NM_000939 |
| UniProt | P01189 |
| Other data | |
| Locus | Chr. 2 p23 |
Adrenocorticotropic hormone (ACTH), also known as corticotropin is a polypeptide tropic hormone produced and secreted by the anterior pituitary gland. It is also used as a medication and diagnostic agent.
It is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress (along with its precursor corticotropin-releasing hormone from the hypothalamus). Its principal effects are increased production and release of cortisol by the cortex of the adrenal gland. ACTH is also related to the circadian rhythm in many organisms.
Deficiency of ACTH is a sign of secondary adrenal insufficiency (suppressed production of ACTH due to a impairment of the pituitary gland or hypothalamus, cf. hypopituitarism) or tertiary adrenal insufficiency (disease of the hypothalamus, with a decrease in the release of corticotropin releasing hormone CRH). Conversely, chronically elevated ACTH levels occur in primary adrenal insufficiency (e.g. Addison's disease) when adrenal gland production of cortisol is chronically deficient. In Cushing's disease a pituitary tumor is the cause of elevated ACTH (from the anterior pituitary) and an excess of cortisol (hypercortisolism) – this constellation of signs and symptoms is known as Cushing's syndrome.
POMC, ACTH and β-lipotropin are secreted from corticotropes in the anterior lobe (or adenohypophysis) of the pituitary gland in response to the hormone corticotropin-releasing hormone (CRH) released by the hypothalamus. ACTH is synthesized from pre-pro-opiomelanocortin (pre-POMC). The removal of the signal peptide during translation produces the 241-amino acid polypeptide POMC, which undergoes a series of post-translational modifications such as phosphorylation and glycosylation before it is proteolytically cleaved by endopeptidases to yield various polypeptide fragments with varying physiological activity. These fragments include:
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