DEFINITION
Proopiomelanocortin is a polypeptide with 241 amino acid residues, precursor of some pituitary hormones.
The release of any of the fragments (eg ACTH) will increase also the release of the other peptides (alpha-MSH, beta-Endorphin etc)
Eg: Sun exposure increases MSH release but also endorphins (pleasure). Alternatively pleasant activity can induce tanning without sun.
Note: Melanocyte-stimulating hormone alpha and beta-endorphin are stored in separate granules in hypothalamic POMC neurons, suggesting that secretion may be under the control of different regulatory mechanisms.
COLI_HUMAN (POMC)
Corticotropin: Stimulates the adrenal glands to release cortisol.
Melanocyte-stimulating hormone alpha: Anorexigenic peptide. Increases the pigmentation of skin by increasing melanin production in melanocytes.
Melanocyte-stimulating hormone beta: Increases the pigmentation of skin by increasing melanin production in melanocytes.
Beta-endorphin: Endogenous orexigenic opiate.
Met-enkephalin: Endogenous opiate.
Excess endorphin?
AGRP
Plays a role in weight homeostasis. Involved in the control of feeding behavior through the central melanocortin system. Acts as alpha melanocyte-stimulating hormone antagonist by inhibiting cAMP production mediated by stimulation of melanocortin receptors within the hypothalamus and adrenal gland. Has very low activity with MC5R (By similarity). Is an inverse agonist for MC3R and MC4R being able to suppress their constitutive activity. It promotes MC3R and MC4R endocytosis in an arrestin-dependent manner.
THE GENE
CHEMICAL STRUCTURE AND IMAGES
When relevant for the function
- Primary structure
- Secondary structure
- Tertiary structure
- Quaternary structure
AA Percentage
Agouti related protein (AGRP)-expressing neurons are a key hypothalamic population that is activated during energy deficit and increases appetite and weight-gain.
Proopiomelanocortin (POMC)-expressing neurons, an intermingled population that suppresses appetite and body weight.
SYNTHESIS AND TURNOVER
mRNA synthesis
protein synthesis
Storage
post-translational modifications
degradation
CELLULAR FUNCTIONS
cellular localization,
biological function
Effects of pro-opiomelanocortin (POMC) on food intake and body weight: mechanisms and therapeutic potential? 2007
lateral hypothalamus (LH)
LH food intake
Paraventricular Nucleus (PVN)
paraventricular nucleus and energy expenditure
** KEGG Pathways
** Human Metabolome Database
* Cell signaling and Ligand transport
* Structural proteins
REGULATION
DIAGNOSTIC USE
