Gastrin family
Encyclopedia
Gastrin
Gastrin
In humans, gastrin is a peptide hormone that stimulates secretion of gastric acid by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the antrum of the stomach, duodenum, and the pancreas...

 and cholecystokinin
Cholecystokinin
Cholecystokinin is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein...

 (CCK) are structurally and functionally related peptide hormones that function as hormonal regulators of various digestive
Digestive
Digestive may refer to:*Digestion, biological process of metabolism*Digestive biscuit, a British semi-sweet biscuit*Digestif, small beverage at the end of a meal...

 processes and feeding behaviors.

They are known to induce gastric secretion, stimulate pancreatic secretion, increase blood circulation and water secretion in the stomach and intestine, and stimulate smooth muscle
Smooth muscle
Smooth muscle is an involuntary non-striated muscle. It is divided into two sub-groups; the single-unit and multiunit smooth muscle. Within single-unit smooth muscle tissues, the autonomic nervous system innervates a single cell within a sheet or bundle and the action potential is propagated by...

 contraction. Originally found in the gut, these hormones have since been shown to be present in various parts of the nervous system
Nervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...

.

Like many other active peptides they are synthesized as larger protein precursors that are enzymatically converted to their mature forms. They are found in several molecular forms due to tissue-specific post-translational processing.

The biological activity of gastrin and CCK is associated with the last five C-terminal residues. One or two positions downstream, there is a conserved sulphated tyrosine residue.

The amphibian caerulein skin peptide, the cockroach leukosulphakinin I and II (LSK) peptides, Drosophila melanogaster putative CCK-homologs Drosulphakinins I and II, cionin, a chicken gastrin/cholecystokinin-like peptide and cionin, a neuropeptide from the protochordate Ciona intestinalis
Ciona intestinalis
Ciona intestinalis is a urochordata , a tunicate widely distributed in Northern European waters. As an invasive species, it has also spread to other parts of the world....

belong to the same family.
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