Cholecystokinin receptors or CCK receptors are a group of G-protein coupled receptors which bind the peptide hormones cholecystokinin

Cholecystokinin

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

 (CCK) or 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...

. There are two different subtypes CCK_A

Cholecystokinin A receptor

The extracellular, N-terminal, domain of this protein adopts a tertiary structure consisting of a few helical turns and a disulfide-cross linked loop...

 and CCK_B

Cholecystokinin B receptor

The cholecystokinin B receptor also known as CCKBR or CCK2 is a protein that in humans is encoded by the CCKBR gene.This gene encodes a G protein-coupled receptor for gastrin and cholecystokinin , regulatory peptides of the brain and gastrointestinal tract...

 which are ~50% homologous

Homology (biology)

Homology forms the basis of organization for comparative biology. In 1843, Richard Owen defined homology as "the same organ in different animals under every variety of form and function". Organs as different as a bat's wing, a seal's flipper, a cat's paw and a human hand have a common underlying...

: Various cholecystokinin antagonist

Cholecystokinin antagonist

A Cholecystokinin antagonist is a specific type of receptor antagonist which blocks the receptor sites for the peptide hormone Cholecystokinin ....

s have been developed and are used in research, although the only drug of this class that has been widely marketed to date is the anti-ulcer drug proglumide

Proglumide

Proglumide is a drug that inhibits gastrointestinal motility and reduces gastric secretions. It acts as a cholecystokinin antagonist, which blocks both the CCKA and CCKB subtypes...

.

protein	gene	tissue distribution	preferred ligand	function
CCKA (CCK1)		primarily gastrointestinal tract Gastrointestinal tract The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. .... , lesser amounts in the CNS Central nervous system The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...	sulfated CCK >> nonsulfated CCK ≈ nonsulfated CCK	stimulation of bicarb secretion, gall bladder emptying and inhibiting gut motility
CCKB (CCK2)		primarily CNS, lesser amounts in the gastrointestinal tract	gastrin ≈ CCK (receptor does not descriminate between sulfated and nonsulfated peptides)	regulation of nociception Nociception Nociception is defined as "the neural processes of encoding and processing noxious stimuli." It is the afferent activity produced in the peripheral and central nervous system by stimuli that have the potential to damage tissue... , anxiety Anxiety Anxiety is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. The root meaning of the word anxiety is 'to vex or trouble'; in either presence or absence of psychological stress, anxiety can create feelings of fear, worry, uneasiness,... , memory Memory In psychology, memory is an organism's ability to store, retain, and recall information and experiences. Traditional studies of memory began in the fields of philosophy, including techniques of artificially enhancing memory....  and hunger Hunger Hunger is the most commonly used term to describe the social condition of people who frequently experience the physical sensation of desiring food.-Malnutrition, famine, starvation:...

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