View source for Biology:Pancreatic polypeptide

{{short description|Protein produced by the endocrine pancreas}}
{{infobox protein
| Name = Pancreatic polypeptide
| caption =
| image = Pancreatic hormone 1TZ5.png
| width =
| HGNCid = 9327
| Symbol = PPY
| AltSymbols =
| EntrezGene = 5539
| OMIM = 167780
| RefSeq = NM_002722
| UniProt = P01298
| PDB =
| ECnumber =
| Chromosome = 17
| Arm = p
| Band = 11.1
| LocusSupplementaryData = -qter
}}
[[File:PancreaticPolypeptide.jpg|thumb|[[Biology:Immunohistochemistry|Immunohistochemistry]] for pancreatic polypeptide in a mouse pancreas, 200×]]
'''Pancreatic polypeptide''' ('''PP''') is a polypeptide secreted by PP cells in the endocrine pancreas. It regulates pancreatic secretion activities, and also impacts [[Biology:Liver|liver]] [[Biology:Glycogen|glycogen]] storage and gastrointestinal secretion. Its secretion may be impacted by certain [[Medicine:Endocrine oncology|endocrine tumours]].

== Gene ==
The '''PPY''' gene encodes an unusually short protein precursor.<ref name=":0">{{cite journal | vauthors = Boel E, Schwartz TW, Norris KE, Fiil NP | title = A cDNA encoding a small common precursor for human pancreatic polypeptide and pancreatic icosapeptide | journal = The EMBO Journal | volume = 3 | issue = 4 | pages = 909–12 | date = April 1984 | pmid = 6373251 | pmc = 557446 | doi = 10.1002/j.1460-2075.1984.tb01904.x }}</ref> This precursor is cleaved to produce pancreatic polypeptide, '''pancreatic icosapeptide''', and a 5- to 7- amino-acid oligopeptide.<ref name=":0" />

== Structure ==
Pancreatic polypeptide consists of 36 amino acids.<ref name=":1" /><ref name=":2">{{Cite book| vauthors = Washabau RJ |title=Canine and Feline Gastroenterology|publisher=Saunders|year=2013|isbn=978-1-4160-3661-6|pages=1–31|language=en|chapter=Chapter 1 - Integration of Gastrointestinal Function|doi=10.1016/B978-1-4160-3661-6.00001-8}}</ref> It has a molecular weight about 4200 [[Dalton (unit)|Da]].<ref name=":1">{{cite journal | vauthors = Lonovics J, Devitt P, Watson LC, Rayford PL, Thompson JC | title = Pancreatic polypeptide. A review | journal = Archives of Surgery | volume = 116 | issue = 10 | pages = 1256–64 | date = October 1981 | pmid = 7025798 | doi = 10.1001/archsurg.1981.01380220010002 }}</ref> It has a similar structure to [[Biology:Neuropeptide Y|neuropeptide Y]].<ref name=":2" />

== Synthesis ==
Pancreatic polypeptide is synthesised and secreted by PP cells (also known as gamma cells or F cells) of the pancreatic islets of the pancreas.<ref name=":2" /><ref>{{Cite book| vauthors = Cozzi B, Huggenberger S, Oelschläger H |title=Anatomy of Dolphins|date=2017-01-01|publisher=[[Company:Academic Press|Academic Press]]|isbn=978-0-12-407229-9|pages=305–338|language=en|chapter=Chapter 7 - Body Control: The Endocrine System and the Peripheral Nervous System|doi=10.1016/B978-0-12-407229-9.00007-5}}</ref> These are found predominantly in the head of the pancreas.{{Citation needed|date=May 2021}}

== Function ==
Pancreatic polypeptide regulates pancreatic secretion activities by both endocrine and exocrine tissues. It also affects hepatic [[Biology:Glycogen|glycogen]] levels and gastrointestinal secretions.

Its secretion in humans is increased after a protein meal, [[Philosophy:Fasting|fasting]], exercise, and acute [[Medicine:Hypoglycemia|hypoglycaemia]], and is decreased by [[Biology:Somatostatin|somatostatin]] and intravenous [[Chemistry:Glucose|glucose]].

Plasma pancreatic polypeptide has been shown to be reduced in conditions associated with increased food intake and elevated in [[Medicine:Anorexia nervosa|anorexia nervosa]]. In addition, peripheral administration of polypeptide has been shown to decrease food intake in rodents.<ref name="pmid12915697">{{cite journal | vauthors = Batterham RL, Le Roux CW, Cohen MA, Park AJ, Ellis SM, Patterson M, Frost GS, Ghatei MA, Bloom SR | display-authors = 6 | title = Pancreatic polypeptide reduces appetite and food intake in humans | journal = The Journal of Clinical Endocrinology and Metabolism | volume = 88 | issue = 8 | pages = 3989–92 | date = August 2003 | pmid = 12915697 | doi = 10.1210/jc.2003-030630 | doi-access = free }}</ref> Pancreatic polypeptide inhibits pancreatic secretion of fluid, [[Chemistry:Bicarbonate|bicarbonate]], and [[Biology:Digestive enzyme|digestive enzyme]]s.<ref name=":2" /> It also stimulates [[Biology:Gastric acid|gastric acid secretion]].<ref name=":2" /> It is the antagonist of [[Biology:Cholecystokinin|cholecystokinin]] and opposes pancreatic secretion stimulated by cholecystokinin.<ref name=":2" /> It may stimulate the [[Biology:Migrating motor complex|migrating motor complex]], synergistic with [[Biology:Motilin|motilin]].<ref name=":2" />

On fasting, pancreatic polypeptide concentration is 80 pg/ml; after the meal, it rises up from 8 to 10 times more; glucose and fats also induce PP's level increase, but on parenteral introduction of those substances, the level of hormones doesn't change. The administration of [[Chemistry:Atropine|atropine]], the [[Medicine:Vagotomy|vagotomy]], blocks pancreatic polypeptide secretion after meals. The excitation of the [[Biology:Vagus nerve|vagus nerve]], the administration of [[Biology:Gastrin|gastrin]], [[Biology:Secretin|secretin]] or cholecystokinin induce PP secretion.

== Clinical significance ==
The secretion of pancreatic polypeptide may be increased by pancreatic tumours ([[Biology:Insulin|insulin]], [[Biology:Glucagon|glucagon]]), by Verner-Morrison syndrome, and by gastrinoma.

== See also ==

* Polypeptide-p
* Pancreas
*List of human cell types derived from the germ layers

== References ==
{{reflist}}

== Further reading ==
{{refbegin}}
* {{cite book| title= Essentials of Human Physiology | vauthors = Nosek TM | chapter= Candidate GI Hormone: Pancreatic Polypeptide |chapter-url=http://humanphysiology.tuars.com/program/section6/6ch2/s6ch2_25.htm |archive-url=https://web.archive.org/web/20160324124828/http://humanphysiology.tuars.com/program/section6/6ch2/s6ch2_25.htm|archive-date=2016-03-24}}
{{refend}}

== External links ==
* {{MeshName|Pancreatic+polypeptide}}

{{Neuropeptides}}
{{Gastrointestinal hormones}}

[[Category:Pancreatic hormones]]

{{Sourceattribution|Pancreatic polypeptide}}