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Pro-Opiomelanocortin (POMC) is a hormone precursor normally produced by the pituitary gland and hypothalamus in the brain, as well as skin cells called melanocytes. It is a compound called a polypeptide that typically undergoes molecular changes initiated by enzymes. The polypeptide hormone structure can be broken up at any of eight different places. Up to 10 different peptides can be processed from POMC, which can influence many kinds of functions within cells.
The polypeptide is coded for by a gene, so its function is typically regulated by the synthesis of Deoxyribonucleic Acid (DNA). Substances derived from POMC can have an effect on adrenal function, energy management, and the immune system. Some also influence the production of melanin, a substance that is responsible for skin pigmentation. Adrenocorticotropin, which stimulates the adrenal glands to release a hormone signaling skin cells to produce melanin, can be formed out of POMC. Melanocyte-Stimulating Hormone (MSH) typically enables the pituitary gland to stimulate melanin production in skin cells, while other variants of MSH can control appetite.
Endorphins, which are involved in various immune processes, are generally formed out of POMC as well. The peptides that are derived from the precursor are typically stored in vesicles within cells. Involved in secreting hormones and other substances, these vesicles are normally directed to the outer membrane in a process called exocytosis. Compounds can be released into the environment and proteins can become part of the membrane in this process.
Exocytosis is the process by which most cells secrete hormones, enzymes, and other proteins. Neurotransmitters in the brain are typically released this way, while hormones responsible for fertilization and immune responses are as well. Cells can also recycle their receptors for proteins in this manner. The microscopic mechanical processes within cells are responsible for the distribution of the many products of POMC. These hormones start as the basic molecules that need to interact with the appropriate enzymes, to produce the required proteins in the first place.
Defects in POMC and the resulting hormones produced may sometimes be caused by genetic mutations. Problems with the adrenal glands can result, and some people with a defective gene can become obese, as hormone abnormalities can cause the body to accumulate too much fat. Red hair pigmentation is sometimes associated with such a defect as well. Under normal circumstances, research has shown that POMC-derived compounds may provide a link between the nervous system and individual immune cells.