| Primary Identifier | IPR004071 | Type | Family |
| Short Name | Cyst_leuk_rcpt |
| description | G protein-coupled receptors (GPCRs) constitute a vast protein family that encompasses a wide range of functions, including various autocrine, paracrine and endocrine processes. They show considerable diversity at the sequence level, on the basis of which they can be separated into distinct groups []. The term clan can be used 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 rhodopsin-like GPCRs (Class A, GPCRA), secretin-like GPCRs (Class B, GPCRB), metabotropic glutamate receptor family (Class C, GPCRC), fungal mating pheromone receptors (Class D, GPCRD), cAMP receptors (Class E, GPCRE) and frizzled/smoothened (Class F, GPCRF) [, , , , ]. GPCRs are major drug targets, and are consequently the subject of considerable research interest. It has been reported that the repertoire of GPCRs for endogenous ligands consists of approximately 400 receptors in humans and mice []. Most GPCRs are identified on the basis of their DNA sequences, rather than the ligand they bind, those that are unmatched to known natural ligands are designated by as orphan GPCRs, or unclassified GPCRs [].The rhodopsin-like GPCRs (GPCRA) 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 acidmetabolism. They can be divided into two classes based on the presence orabsence of a cysteinyl group. Leukotriene B4 (LTB4) does not contain such agroup, whereas LTC4, LTD4, LTE4 and LTF4 are cysteinyl leukotrienes.Cysteinyl leukotrienes (CysLTs), previously known as the "slow reactingsubstance of anaphylaxis", are produced predominantly by myeloid cellsassociated with inflammatory responses []. They are the most potent bronchoconstrictors known and also have pro-inflammatory effects, makingthem 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, due 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 [, ]. |
