Protein Domain : [Phe13]-bombesin receptor IPR000401

Type	Family
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 [ , , ].This family represents a group of animal proteins that play important roles in both physiological state and diseases [ ]. Proteins in this family are frequently overexpressed by common tumors. Consequently, they are considered a possible therapeutic target in several tumors, particularly in prostate, breast, and lung cancer, but its role in some CNS/neural tumors (gliomas, neuroblastomas, medulloblastomas) may also be of interest []. This small family represents [Phe13]-bombesin receptor (Bombesin receptor suptype 4, BRS4) from Bombina orientalis (oriental fire-bellied toad) and similar proteins from amphibia. The recently-identified BRS-4 bombesin receptor subtype is found only in the brain, primarily in the cortex and forebrain, and at low levels in themidbrain. The relative rank potency of bombesin-like peptides for this receptor is [Phe13]bombesin >[Leu13]bombesin >GRP >neuromedin B [ ].
Short Name	BRS4