H4 receptor

The H4 histamine receptor was first published by Nguyen et al in March of 2001, who also published the gene encoded it in a search of the GenBank databases. Like the other three histamine receptors, it is also a G protein-coupled receptor.

Location
H4 is highly expressed in bone marrow and white blood cells and regulates zymosan-induced neutrophil release from bone marrow and subsequent infiltration in the pleurisy model along with L-selectin. It is also expressed in the colon, liver, lung, small intestine, spleen, testes, thymus, tonsils, and trachea.

Functions
They have been shown to mediate mast cell chemotaxis. ...and more

High affinity substances
The following substances have been found to bind with high affinity to this receptor:
 * amitriptyline
 * chlorpromazine
 * doxepin
 * promethazine
 * cinnarizine

Moderate affinity substances
The following substances have been found to bind with moderate affinity to this receptor:
 * cyproheptadine
 * clemizole
 * mianserin
 * clozapine
 * chlorpheniramine
 * histamine

Weak affinity substances
The following substances have been found to bind with weak affinity to this receptor:
 * imetit
 * pheniramine
 * dimaprit