Rhodopsin-like receptors are a family of proteins that comprise the largest group of G protein-coupled receptors.

Scope

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. GPCRs are usually described as "superfamily" because 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 superfamily members include the rhodopsin-like GPCRs (this family), the secretin-like GPCRs, the cAMP receptors, the fungal mating pheromone receptors, and the metabotropic glutamate receptor family. There is a specialised database for GPCRs.

Function

The rhodopsin-like GPCRs themselves represent a widespread protein family that includes hormone, neuropeptide, 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.

Classes

Rhodopsin-like GPCRs have been classified into the following 19 subgroups (A1-A19) based on a phylogenetic analysis.

Subfamily A1

Subfamily A2

Subfamily A3

Subfamily A4

Subfamily A5

Subfamily A6

Subfamily A7

Subfamily A8

Subfamily A9

Subfamily A10

Subfamily A11

Subfamily A12

Subfamily A13

Subfamily A14

Subfamily A15

Subfamily A16

Subfamily A17

Subfamily A18

Subfamily A19

Unclassified