Class C GPCR
# Class C GPCR

The class C G-protein-coupled receptors (InterPro: IPR000337) are a class of G-protein coupled receptors that include the metabotropic glutamate receptors (InterPro: IPR000162) and several additional receptors.

Structurally they are composed of four elements; an N-terminal signal sequence; a large hydrophilic extracellular agonist-binding region containing several conserved cysteine residues which could be involved in disulphide bonds; a shorter region containing seven transmembrane domains; and a C-terminal cytoplasmic domain of variable length. This protein family includes metabotropic glutamate receptors, the extracellular calcium-sensing receptors, the gamma-amino-butyric acid (GABA) type B receptors, and the vomeronasal type-2 receptors.

## Subfamilies

### Calcium-sensing receptor-related

* extracellular calcium-sensing receptor-related InterPro: IPR000068
   * Calcium-sensing receptor (CASR)
   * GPRC6A (GPRC6A)

### $GABA_B$ receptors

* $GABA_B$ receptor (gamma-aminobutyric acid) InterPro: IPR002455
   * $GABA_B$ receptor 1 (GABBR1)
   * $GABA_B$ receptor 2 (GABBR2)

### Metabotropic glutamate receptors

* Metabotropic glutamate receptors (mGluR) InterPro: IPR000162
   * $mGluR_1$ (GRM1)
   * $mGluR_2$ (GRM2)
   * $mGluR_3$ (GRM3)
   * $mGluR_4$ (GRM4)
   * $mGluR_5$ (GRM5)
   * $mGluR_6$ (GRM6)
   * $mGluR_7$ (GRM7)
   * $mGluR_8$ (GRM8)

### RAIG

* Retinoic acid-inducible orphan G protein-coupled receptors (RAIG)
   * $RAIG_1$ (GPRC5A)
   * $RAIG_2$ (GPRC5B)
   * $RAIG_3$ (GPRC5C)
   * $RAIG_4$ (GPRC5D)

### Taste receptors

* Taste receptor
   * Taste receptor, type 1, member 1 (TAS1R1)
   * Taste receptor, type 1, member 2 (TAS1R2)
   * Taste receptor, type 1, member 3 (TAS1R3)

### Orphan

* Class C Orphan receptors
   * GPR158 (GPR158)
   * GPR179 (GPR179)
   * GPR156 (GPR156)

### Other

* Bride of sevenless protein InterPro: IPR002956
* Vomeronasal receptor, type 2 InterPro: IPR004073
