| Type: | Family | Name: | Cysteinyl leukotriene receptor 1 |
| Description: | G protein-coupled receptors (GPCRs) constitute a vast protein family that encompasses a wide range of functions (including various autocrine, para-crine and endocrine processes). They show considerable diversity at the sequence level, on the basis of which they can be separated into distinct groups. We use the term clan to describe the GPCRs, as they embrace a group of families for which there are indications of evolutionary relationship, but between which there is no statistically significant similarity in sequence []. The currently known clan members include the rhodopsin-like GPCRs, the secretin-like GPCRs, the cAMP receptors, the fungal mating pheromone receptors, and the metabotropic glutamate receptor family.The rhodopsin-like GPCRs themselves represent a widespread protein family that includes hormone, neurotransmitter and light receptors, all of which transduce extracellular signals through interaction with guanine nucleotide-binding (G) proteins. Although their activating ligands vary widely in structure and character, the amino acid sequences of the receptors are very similar and are believed to adopt a common structural framework comprising 7 transmembrane (TM) helices [, , ].Leukotrienes (LT) are potent lipid mediators derived from arachidonic acid metabolism. They can be divided into two classes based on the presence or absence of a cysteinyl group. Leukotriene B4 (LTB4) does not contain such a group, whereas LTC4, LTD4, LTE4 and LTF4 are cysteinyl leukotrienes.Cysteinyl leukotrienes (CysLTs), previously known as the "slow reacting substance of anaphylaxis", are produced predominantly by myeloid cells associated with inflammatory responses []. They are the most potent bronchoconstrictors known and also have pro-inflammatory effects, making them important mediators in the pathophysiology of human asthma []. CysLTs have also been implicated in a variety of other diseases, such as allergic rhinitis, inflammatory bowel disease and psoriasis []. Pharmacological studies of the effects of CysLTs have provided evidence for the existence of at least 2 distinct receptor subtypes, belonging to the G protein-coupled receptor family, designated CysLT1 and CysLT2 [, ]. CysLT1 is thought to mediate bronchospasm, plasma exudation, vasoconstriction, mucus secretion and eosinophil recruitment []. CysLT2 is less well defined, owing to a lack of specific agonists and antagonists, but is thought to mediate some of the vascular effects attributed to CysLTs [, ]. Both receptor subtypes have now been cloned [, ].CysLT1 has a much higher affinity for LTD4 than for the other cysteinyl leukotrienes and, upon activation, stimulates phosphatidyl inositol hydrolysis and increases in intracellular calcium. The receptor is expressed at highest levels in the spleen and in peripheral blood leukocytes, with lower levels in the lung, placenta, small intestine, pancreas, colon and heart [, , ]. | Short Name: | CLT1_recept |
