The class C G-protein-coupled receptors () are a class of
G-protein coupled receptors
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily related ...
that include the
metabotropic glutamate receptor
The metabotropic glutamate receptors, or mGluRs, are a type of glutamate receptor that are active through an indirect metabotropic receptor, metabotropic process. They are members of the group C GPCR family, group C family of G-protein-coupled r ...
s () and several additional receptors.
Structurally they are composed of four elements; an
N-terminal
The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the amin ...
signal sequence; a large hydrophilic extracellular agonist-binding region containing several conserved
cysteine
Cysteine (; symbol Cys or C) is a semiessential proteinogenic amino acid with the chemical formula, formula . The thiol side chain in cysteine enables the formation of Disulfide, disulfide bonds, and often participates in enzymatic reactions as ...
residues which could be involved in
disulphide bonds
In chemistry, a disulfide (or disulphide in British English) is a compound containing a functional group or the anion. The linkage is also called an SS-bond or sometimes a disulfide bridge and usually derived from two thiol groups.
In inorg ...
; a shorter region containing seven transmembrane domains; and a
C-terminal
The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, carboxy tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When t ...
cytoplasmic domain of variable length.
This
protein family
A protein family is a group of evolutionarily related proteins. In many cases, a protein family has a corresponding gene family, in which each gene encodes a corresponding protein with a 1:1 relationship. The term "protein family" should not be ...
includes
metabotropic glutamate receptor
The metabotropic glutamate receptors, or mGluRs, are a type of glutamate receptor that are active through an indirect metabotropic receptor, metabotropic process. They are members of the group C GPCR family, group C family of G-protein-coupled r ...
s, the extracellular
calcium-sensing receptor
The calcium-sensing receptor (CaSR) is a Class C G-protein coupled receptor which senses extracellular levels of calcium ions. It is primarily expressed in the parathyroid gland, the renal tubules of the kidney, pancreatic islets and the br ...
s, 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
**
Calcium-sensing receptor
The calcium-sensing receptor (CaSR) is a Class C G-protein coupled receptor which senses extracellular levels of calcium ions. It is primarily expressed in the parathyroid gland, the renal tubules of the kidney, pancreatic islets and the br ...
()
**
GPRC6A
G protein-coupled receptor family C group 6 member A (GPRC6A) is a protein that in humans is encoded by the ''GPRC6A'' gene. This protein functions as a receptor of L-α-amino acids, cations (e.g., calcium), osteocalcin, and steroids. It is a mem ...
()
GABAB receptors
*
GABAB receptor (gamma-aminobutyric acid)
**
GABAB receptor 1 ()
**
GABAB receptor 2 ()
Metabotropic glutamate receptors
*
Metabotropic glutamate receptor
The metabotropic glutamate receptors, or mGluRs, are a type of glutamate receptor that are active through an indirect metabotropic receptor, metabotropic process. They are members of the group C GPCR family, group C family of G-protein-coupled r ...
s (mGluR)
**
mGluR1 ()
**
mGluR2 ()
**
mGluR3 ()
**
mGluR4 ()
**
mGluR5 ()
**
mGluR6 ()
**
mGluR7 ()
**
mGluR8 ()
RAIG
*
Retinoic acid-inducible orphan G protein-coupled receptors (RAIG)
**
RAIG1 ()
**
RAIG2 ()
**
RAIG3 ()
**
RAIG4 ()
Taste receptors
*
Taste receptor
A taste receptor or tastant is a type of cellular receptor that facilitates the sensation of taste. When food or other substances enter the mouth, molecules interact with saliva and are bound to taste receptors in the oral cavity and other locat ...
**
Taste receptor, type 1, member 1 ()
**
Taste receptor, type 1, member 2 ()
**
Taste receptor, type 1, member 3 ()
Orphan
* Class C
Orphan receptor
In biochemistry, an orphan receptor is a protein that has a similar structure to other identified receptors but whose endogenous ligand has not yet been identified. If a ligand for an orphan receptor is later discovered, the receptor is referred ...
s
**
GPR158 ()
**
GPR179 ()
**
GPR156 ()
Other
* Bride of sevenless protein
*
Vomeronasal receptor
Vomeronasal receptors are a class of olfactory receptors that putatively function as receptor (biology), receptors for pheromones. Pheromones have evolved in all animal phyla, to signal sex and dominance status, and are responsible for stereotypi ...
, type 2
References
G protein-coupled receptors
{{transmembranereceptor-stub