Cholecystokinin
| Cholecystokinin | ||
|---|---|---|
| Properties of human protein | ||
| Mass / length primary structure | 58 aa; 33 aa; 22 aa; 8 aa | |
| Precursor | Procholecystokinin, 95 aa | |
| Identifier | ||
| Gene names | CCK ; MGC117187 | |
| External IDs | ||
| Occurrence | ||
| Parent taxon | Jaws | |
| Orthologue | ||
| human | mouse | |
| Entrez | 885 | 12424 |
| Ensemble | ENSG00000187094 | ENSMUSG00000032532 |
| UniProt | P06307 | Q53WS9 |
| Refseq (mRNA) | NM_000729 | NM_031161 |
| Refseq (protein) | NP_000720 | NP_112438 |
| Gene locus | Chr 3: 42.27 - 42.28 Mb | Chr 9: 121.34 - 121.34 Mb |
| PubMed search | 885 |
12424
|
Cholecystokinin (CCK) or pancreozymin (PZ or PKZ) is a peptide hormone found in the gastrointestinal tract . It also plays an important role in the brain as a neurotransmitter . Literally translated, cholecystokinin means gallbladder mover in German . Cholecystokinin is also involved in the central nervous system in triggering the feeling of satiety .
structure
CCK is composed of a different number of amino acids (z. B. CCK58, CCK33, CCK8), which from the prohormone Procholecystokinin (95 amino acids) processed to be. Its structure is similar to gastrin . The last five C-terminal amino acids are identical to those of gastrin.
Place of education
It is produced in the upper duodenum (duodenum) and in the subsequent jejunum (empty intestine) in special enteroendocrine cells, the so-called I cells. The release of the hormone is stimulated by fatty and amino acids in the food pulp.
Target organ and mode of action
The target organs of cholecystokinin are the gall bladder and the pancreas . CCK stimulates the pancreatic secretion and at the same time causes a contraction of the smooth muscles of the gallbladder wall as well as the relaxation of the musculus sphincter Oddii and thereby the flow of bile. It stimulates the peristalsis of the small intestine and large intestine . CCK reduces the effect of gastrin in the stomach by competing for displacement from the CCKB receptor, thereby reducing hydrochloric acid production. In addition, it plays a role in the development of anxiety and panic as well as anxiety disorders . It is also responsible for the feeling of satiety by acting on the nucleus tractus solitarii (NTS), which is located in the medulla oblongata belonging to the brain stem .
Cholecystokinin receptors
The effects of the CCK on the various cells are mediated by membrane receptors . Analogous to the discovery of CCK, its receptors were also first detected in the digestive tract (CCK-A receptor: A - alimentary , mainly in the gall bladder and pancreas ). It was not until 1980 that receptors for cholecystokinin could also be detected in the brain (CCK-B receptor: B - brain , mainly in the brain , but also in the stomach ).
In 1992 the genes of both the CCK-A receptor and the CCK-B receptor were discovered and cloned one after the other. This enabled the protein structure of both receptors to be clarified at the same time. Both receptors belong to the superfamily of G-protein-coupled receptors . They consist of seven transmembrane domains and their protein structure is 48% identical. However, the genetic information is on different chromosomes (CCKAR on Chr. 4, CCKBR on Chr. 11). The CCK-B receptor is genetically identical to the gastrin receptor and only differs in 5 amino acids due to a splicing variant .
Research history
Cholecystokinin was first detected in 1928/1929 by the US physiologist Andrew Conway Ivy and the neurosurgeon Eric Oldberg . In 1941, Harper and Raper discovered the effects of a hormone they called pancreozymin. 25 years later it was isolated and purified by Johan Erik Jorpes and Viktor Mutt, who discovered that cholecystokinin and pancreozymin are identical.
swell
- ↑ UniProt P06307
- ↑ AH Saito, H. Sankaran, ID Goldine, JA Williams: Cholecystokinin receptors in the brain: Characterization and distribution. In: Science. 208, 1980, pp. 1155-1156.
- ↑ SA Wank, JR Pisegna, A. de Weerth: cholecystokinin receptor family. Molecular cloning, structure, and functional expression in rat, guinea pig, and human. In: Ann. NY Acad. Sci. 713, 1994, pp. 49-66.
- ↑ I. Song, DR Brown, RN Wiltshire, I. Gantz, JM Trent, T. Yamada: The human gastrin / cholecystokinin type B receptor gene: alternative splice donor site in exon 4 generates two variant mRNAs. In: Proc. Natl. Acad. Sci. USA 90, 1993, pp. 9085-9089.
- ↑ John Malone Howard, Walter Hess: History of the Pancreas: Mysteries of a Hidden Organ . Springer 2002, ISBN 0-306-46742-9 , p. 93.