Gastric inhibitory polypeptide
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| Gastric inhibitory polypeptide
| |
| Identifiers | |
| Symbol | GIP |
| Entrez | 2695 |
| HUGO | 4270 |
| OMIM | 137240 |
| RefSeq | NM_004123 |
| UniProt | P09681 |
| Other data | |
| Locus | Chr. 17 q21.3-q22 |
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Gastric inhibitory polypeptide (GIP), also known as the glucose-dependent insulinotropic peptide is a member of the secretin family of hormones.
GIP, along with glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2), belong to a class of molecules referred to as incretins
Synthesis and transport
GIP is derived from a 153-amino acid proprotein encoded by the GIP gene and circulates as a biologically active 42-amino acid peptide. It is synthesized by K cells, which are found in the mucosa of the duodenum and the jejunum of the gastrointestinal tract.
Like all hormones, it is transported by blood.
Gastric inhibitory polypeptide receptors are seven-transmembrane proteins found on beta-cells in the pancreas.
Function
It has traditionally been called gastrointestinal inhibitory peptide or gastric inhibitory peptide and was believed to neutralize stomach acid to protect the small intestine from acid damage, reduce the rate at which food is transferred through the stomach, and inhibit the GI motility and secretion of acid. However, it was discovered that these effects are only achieved with higher-than-normal physiological level, and that these results naturally occur in the body through a similar hormone, secretin.
It is now believed that the function of GIP is to induce insulin secretion, which is primarily stimulated by hyperosmolarity of glucose in the duodenum. After this discovery, some researchers prefer the new name of glucose-dependent insulinotropic peptide, while retaining the Acronym "GIP." The amount of insulin secreted is greater when glucose is administered orally than intravenously.
GIP is also thought to have significant effects on fatty acid metabolism through stimulation of lipoprotein lipase activity in adipocytes. GIP release has been demonstrated in the ruminant animal and may play a role in nutrient partitioning in milk production (lipid metabolism). GIP is secreted in response to the first maternal feed (colostrum) in goat kids-gip being measured via umbilical vein before its closure. For ethical reasons GIP secretion has only been demonstrated in humans at approx 10 days of age. In respect to the role of GIP in lipid metabolism, supraphysiological levels have shown a lipogenic action, however the action of collagenase in experimental protocols is known to degrade GIP/ GIP receptors. GIP is part of the diffuse endocrine system and consequently difficult to demonstrate physiological or clinical effects. In comparison to insulin its effects are very subtle.
Pathology
It has been found that Type 2 diabetics are not responsive to GIP. In a research involving knockout mice, it was found that absence of the GIP receptors correlates with resistance to obesity.
References
External links
- MeSH Gastric+inhibitory+polypeptide
- Gastric+inhibitory+polypeptide at eMedicine Dictionary
- http://web.indstate.edu/thcme/mwking/peptide-hormones.html#gastrin
Digestive system, physiology: gastrointestinal physiology | |
|---|---|
| Enteric nervous system | Meissner's plexus - Auerbach's plexus |
| Exocrine | Chief cells (Pepsinogen) - Parietal cells (Gastric acid, Intrinsic factor) - Goblet cells (Mucus) |
| Endocrine/paracrine | G cells (gastrin), D cells (somatostatin) - ECL cells (Histamine) - enterogastrone: I cells (CCK), K cells (GIP), S cells (secretin) |
| Border | Brunner's glands - Paneth cells - Enterocytes |
| Fluids | Saliva - Bile - Intestinal juice - Gastric juice - Pancreatic juice |
| Processes | Swallowing - Vomiting - Peristalsis (Interstitial cell of Cajal) - Migrating motor complex - Borborygmus - Gastrocolic reflex - Segmentation contractions - Defecation |
Hormones: gastrointestinal hormones |
|---|
| CCK - EGF - GIP - Gastrin releasing peptide - Gastrins - Proglucagon - Motilin - Peptide YY -Prokineticin - Secretin - VIP |
Peptides: neuropeptides | |
|---|---|
| Hypothalamic | Somatostatin - CRH - GnRH - GHRH - Orexins - TRH - POMC (ACTH, MSH, Lipotropin) |
| Gastrointestinal hormones | Cholecystokinin - Gastric inhibitory polypeptide - Gastrin - Motilin - Secretin - Vasoactive intestinal peptide |
| Other hormones | Vasopressin - Calcitonin - |
| Other | Angiotensin - Bombesin/Neuromedin B - Calcitonin gene-related peptide - Carnosine - Delta sleep-inducing peptide - FMRFamide - Galanin - Gastrin releasing peptide - Kinins (Bradykinin, Tachykinins ) - Neuromedin (B, N, U) - Neuropeptide Y - Neurophysins - Neurotensin - Opioid peptide - Pancreatic polypeptide - Pituitary adenylate cyclase activating peptide |
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
