Metabotropic receptors

Metabotropic receptors are receptors coupled to G-proteins that are designed for hydrophilic substances. The receptor is made up of a glycoprotein chain that passes through the membrane seven times. Signal molecules bind to the N-terminus of the chain.

Construction of receptors
Extracellular domain: ligand binding site

Transmembrane domain: a hydrophobic AMK that forms 7 α helices

Intracytoplasmic domain: interaction with G-proteins

G-protein: consists of three subunits: α,β,γ. G-proteins are bound to the receptor on the inside of the cytoplasmic membrane by means of lipid anchors (covalently bound fatty acids).

The ``α subunit'' binds the corresponding guanosine nucleotide and has GTPase activity.

Function of receptors
Activated state: bound GTP

Inactive Status: tied to GDP

Activation process: the ligand binds to the receptor, GDP is exchanged for GTP, the α subunit with GTP detaches and travels to the appropriate effector. Metabotropic receptors influence the production of second messengers.

Examples of metabotropic receptors

 * dopamine receptor
 * GABA receptor – type B
 * glucagon receptors
 * secretin receptors
 * metabotropic glutamate receptor

Related Articles

 * Cell Signaling
 * G-proteins
 * Second Messengers
 * GABA