Peptide hormone
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217597253
2008-06-06T19:20:33Z
Reneeholle
4620734
remove template; now referenced
'''Peptide hormones''' are a class of [[peptide|peptides]] that are secreted into the blood stream and have [[endocrine]] functions in living animals.<ref>[http://books.google.com/books?id=hrp1AAAACAAJ ''Peptide Hormone Secretion/Peptide Hormone Action: A Practical Approach,''] K. Siddle, J. C. Hutton, Oxford University Press, 1991, ISBN:0199630739.</ref>
Like other [[protein]]s, peptide [[hormone]]s are synthesized from [[amino acid]]s according to an [[mRNA]] template, which is itself synthesized from a [[DNA]] template inside the [[cell (biology)|cell]]'s [[Cell nucleus|nucleus]]. Peptide hormone precursors (pre-prohormones) are then processed in several stages, typically in the [[endoplasmic reticulum]], including removal of the [[N-terminal]] [[signal sequence]] and sometimes [[glycosylation]], resulting in [[prohormone]]s. The prohormones are then packaged into membrane-bound secretory vesicles, which can be secreted from the cell by [[exocytosis]] in response to specific stimuli.<ref>[http://books.google.com/books?id=QmNrJgAACAAJ&dq=peptide+hormone ''Peptide Hormone Secretion: A Practical Approach,''] J. C. Hutton, Oxford University Press, 1991, ISBN:0199630682.</ref>
These prohormones often contain superfluous amino acid residues that were needed to direct folding of the hormone molecule into its active configuration but have no function once the hormone folds. Specific [[endopeptidase]]s in the cell cleave the prohormone just before it is released into the [[blood]] stream, generating the mature hormone form of the molecule. Mature peptide hormones then diffuse through the blood to all of the cells of the body, where they interact with specific [[receptor (biochemistry)|receptor]]s on the surface of their target cells. Some peptide/[[protein hormone]]s ([[angiotensin | angiotensin II]], [[basic fibroblast growth factor]]-2, [[parathyroid hormone-related protein]]) also interact with [[intracellular]] receptors located in the [[cytoplasm]] or [[Cell nucleus|nucleus]] by an [[intracrine]] mechanism.<ref>[http://books.google.com/books?id=TlC5Hfl04sMC ''The Endocrine System in Sports and Exercise,''] William J. Kraemer, Alan D. Rogol, Blackwell Publishing, 2005, ISBN:1405130172.</ref>
==Notable peptide hormones==
Several important peptide hormones are secreted from the pituitary gland. The [[anterior pituitary]] secretes [[luteinizing hormone]] and [[follicle-stimulating hormone]], which act on the [[gonads]], [[prolactin]], which acts on the [[mammary gland]], [[adrenocorticotrophic hormone]] (ACTH), which acts on the [[adrenal cortex]] to regulate the secretion of [[glucocorticoids]], and [[growth hormone]], which acts on [[bone]], [[muscle]], and the [[liver]]. The [[posterior pituitary]] gland secretes [[antidiuretic hormone]], also called vasopressin, and [[oxytocin]]. Peptide hormones are produced by many different organs and tissues, however, including the [[heart]] ([[atrial-natriuretic peptide]] (ANP) or atrial natriuretic factor (ANF)) and [[pancreas]] ([[insulin]] and [[somatostatin]]), the gastrointestinal tract ([[cholecystokinin]], [[gastrin]]), and [[adipose tissue]] stores ([[leptin]]).<ref>[http://books.google.com/books?id=UbL2MZ9xI7oC ''Dictionary of Biological Psychology,''] Philip Winn, Taylor and Francis, 2001, ISBN:0415136067.</ref><ref>[http://books.google.com/books?id=RChYAAAAMAAJ&pgis=1 ''McGraw-Hill Encyclopedia of Science & Technology,''] Sybil P. Parker, McGraw-Hill, 1997, ISBN:0079115047.</ref>
Some [[neurotransmitters]] are secreted and released in a similar fashion to peptide hormones, and some '[[neuropeptides]]' may be used as neurotransmitters in the [[nervous system]] in addition to acting as hormones when released into the blood. When a peptide hormone binds to receptors on the surface of the cell, a [[second messenger]] appears in the [[cytoplasm]], which triggers intracellular responses.<ref>[http://books.google.com/books?id=CLSmMU7ErFMC ''The Practice of Medicinal Chemistry,''] C. G. Wermuth, Academic Press, 2003, ISBN:0127444815.</ref>
==References==
{{reflist}}
{{Hormones}}
[[Category:Peptide hormones]]
[[de:Proteohormon]]
[[es:Hormona peptídica]]
[[fr:Hormone peptidique]]
[[nl:Peptidehormoon]]
[[ja:ペプチドホルモン]]
[[pl:Hormony peptydowe]]
[[sv:Peptidhormon]]
[[zh:肽类激素]]