| Primary Identifier | IPR008362 | Type | Family |
| Short Name | MCH2_receptor |
| 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 [, , ].Melanin-concentrating hormone (MCH) is a cyclic peptide originallyidentified in teleost fish []. In fish, MCH is released from thepituitary and causes lightening of skin pigment cells through pigmentaggregation. In mammals, MCH is predominantly expressed in thehypothalamus, and functions as a neurotransmitter in the control of a rangeof functions. A major role of MCH is thought to be in the regulation offeeding: injection of MCH into rat brains stimulates feeding; expression ofMCH is upregulated in the hypothalamus of obese and fasting mice; and micelacking MCH are lean and eat less. MCH and alpha melanocyte-stimulatinghormone (alpha-MSH) have antagonistic effects on a number of physiologicalfunctions. Alpha-MSH darkens pigmentation in fish and reduces feeding inmammals, whereasMCH increases feeding [].Two G protein-coupled receptors, MCH1 and MCH2, have recently beenidentified as receptors for the melanin-concentrating hormone. |
