User:Cboursnell/Sandbox/7TM GPCR Srab

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. Chemoperception is one of the central senses of soil nematodes like C. elegans which are otherwise 'blind' and 'deaf'. 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. Many of these proteins have homologues in Caenorhabditis briggsae.

Srab is part of the Sra superfamily of chemoreceptors. The expression pattern of the srab genes is biologically intriguing. Of the six promoters successfully expressed in transgenic organisms, one was exclusively expressed in the tail phasmid neurons, two were exclusively expressed in a head amphid neuron, and two were expressed both in the head and tail neurons as well as a limited number of other cells.