| 词条 | Xenin |
| 释义 |
| name = Coatomer subunit alpha | image = | width = | caption = | Symbol = COPA | AltSymbols = | IUPHAR_id = | ATC_prefix = | ATC_suffix = | ATC_supplemental = | CAS_number = | CAS_supplemental = | DrugBank = | EntrezGene = | HGNCid = | OMIM = | PDB = | RefSeq = NP_001091868 | UniProt = P53621 | ECnumber = | Chromosome = 1 | Arm = q | Band = 23.2 | LocusSupplementaryData = }} Xenin is a peptide hormone produced by a subpopulation of chromogranin A-positive endocrine cells in the mucous membrane of the duodenum. The peptide has been found in humans, dogs, pigs, rats, and rabbits. In humans, xenin circulates in the blood plasma.[1] There is a relationship between peaks of xenin concentration in the plasma and the third phase of the Migrating Motor Complex. For example, infusion of synthetic xenin in fasting volunteers will cause phase III activity. After a meal (the 'postprandial state'), infusion of xenin increases both frequency and the percentage of aborally propagated contractions. In higher concentrations xenin stimulates exocrine pancreatic secretion and inhibits the gastrin-stimulated secretion of acid in dogs. Xenin is also produced in neuroendocrine tumors of the duodenal mucosa. In vitro, xenin interacts with the neurotensin receptor 1. Structure and sequenceXenin is a 25-amino acid polypeptide. The amino acid sequence of xenin is identical to the N-terminal end of cytoplasmic coatomer subunit alpha,[2] from which xenin can be cleaved by aspartic proteases. Xenin is structurally related to the amphibian peptide xenopsin and to the neuropeptide neurotensin. ProxeninProxenin is the precursor to xenin. It is a 35-amino acid polypeptide. Like xenin, its amino acid sequence exactly matches the N-terminus of coatomer subunit alpha.[2] As a drug targetXenin promotes beta-cell survival and xenin has been evaluated in animal models of obesity and diabetes where it has demonstrated an antidiabetic potential.[3] In humans, co-administration of xenin-25 and gastric inhibitory polypeptide (GIP) reduces postprandial glycemia by delaying gastric emptying. [4] References1. ^{{cite journal | vauthors = Feurle GE, Hamscher G, Kusiek R, Meyer HE, Metzger JW | title = Identification of xenin, a xenopsin-related peptide, in the human gastric mucosa and its effect on exocrine pancreatic secretion | journal = J. Biol. Chem. | volume = 267 | issue = 31 | pages = 22305–9 |date=November 1992 | pmid = 1429581 | doi = }} 2. ^1 UniProtKB/Swiss-Prot entry P53621 COPA_HUMAN 3. ^{{cite journal | vauthors = Craig SL, Gault VA, Irwin N | title = Emerging therapeutic potential for xenin and related peptides in obesity and diabetes | journal = Diabetes/metabolism Research and Reviews | volume = 34 | issue = 6 | pages = e3006 | date = September 2018 | pmid = 29633491 | doi = 10.1002/dmrr.3006 }} 4. ^{{cite journal | vauthors = Hussain MA, Akalestou E, Song WJ | title = Inter-organ communication and regulation of beta cell function | journal = Diabetologia | volume = 59 | issue = 4 | pages = 659–67 | date = April 2016 | pmid = 26791990 | pmc = 4801104 | doi = 10.1007/s00125-015-3862-7 }} Further reading{{refbegin}}
1 : Intestinal hormones |
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