7TM GPCR, serpentine receptor class b (Srb) (IPR002184)

Short name: 7TM_GPCR_serpentine_rcpt_Srb

Overlapping homologous superfamilies


Family relationships



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 [PMID: 12679517]. 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 [PMID: 8170923]. 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) [PMID: 8170923, PMID: 8081729, PMID: 15914470, PMID: 18948278, PMID: 16753280]. 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 [PMID: 12679517]. 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 [PMID: 23020293].

The nematode Caenorhabditis elegans has only 14 types of chemosensory neuron, yet is able to sense and respond to several hundred different chemicals because each neuron detects several stimuli [PMID: 10580986]. Chemoperception is one of the central senses of soil nematodes like C. elegans which are otherwise 'blind' and 'deaf' [PMID: 18050473]. Chemoreception in C. elegans is mediated by members of the seven-transmembrane G-protein-coupled receptor class (7TM GPCRs). More than 1300 potential chemoreceptor genes have been identified in C. elegans, which are generally prefixed sr for serpentine receptor. The receptor superfamilies include Sra (Sra, Srb, Srab, Sre), Str (Srh, Str, Sri, Srd, Srj, Srm, Srn) and Srg (Srx, Srt, Srg, Sru, Srv, Srxa), as well as the families Srw, Srz, Srbc, Srsx and Srr [PMID: 7585938, PMID: 18050473, PMID: 15618405]. Many of these proteins have homologues in Caenorhabditis briggsae.

This entry represents serpentine receptor class b (Srb) from the Sra superfamily [PMID: 15618405]. Srb receptors contain 6-8 hydrophobic, putative transmembrane, regions and can be distinguished from other 7TM GPCR receptors by their own characteristic TM signatures.

GO terms

Biological Process

GO:0007606 sensory perception of chemical stimulus

Molecular Function

GO:0004888 transmembrane signaling receptor activity

Cellular Component

GO:0016021 integral component of membrane

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.