GABA Receptors
GABA

Author: Gianpiero Pescarmona
Date: 24/07/2010

Description

The GABA receptors are a class of receptors that respond to the neurotransmitter gamma-aminobutyric acid (GABA), the chief inhibitory neurotransmitter in the vertebrate central nervous system.

There are two classes of GABA receptors:

  • GABAA : GABAA receptors are ligand-gated ion channels (also known as ionotropic receptors)
  • GABAB : GABAB receptors are G protein-coupled receptors (also known as metabotropic receptors).

GABAA Receptors

The subset of GABAA receptors that also bind benzodiazepines are referred to as benzodiazepine receptors (BzR). The GABAA receptor is a heteromer composed of five subunits, most commonly two α's, two β's and one γ (α2β2γ). For each subunit, many subtypes exist (α1-6, β1-3 and γ1-3). GABAA receptors that are made up of different combinations of subunit subtypes have different properties, different distributions in the brain and different activities relative to pharmacological and clinical effects. Benzodiazepines bind at the interface of the α and γ subunits on the GABAA receptor. Binding also requires that alpha subunits contain a histidine amino acid residue, (i.e., α1, α2, α3 and α5 containing GABAA receptors). For this reason, benzodiazepines show no affinity for GABAA receptors containing α4 and α6 subunits with an arginine instead of a histidine residue.

Once bound to the benzodiazepine receptor, the benzodiazepine ligand locks the benzodiazepine receptor into a conformation in which it has a greater affinity for the GABA neurotransmitter. This increases the frequency of the opening of the associated chloride ion channel and hyperpolarizes the membrane of the associated neuron. The inhibitory effect of the available GABA is potentiated, leading to sedatory and anxiolytic effects. Furthermore, different benzodiazepines can have different affinities for BzRs made up of different collection of subunits. For instance, those with high activity at the α1 are associated with stronger hypnotic effects, whereas those with higher affinity for GABAA receptors containing α2 and/or α3 subunits have good anti-anxiety activity.

DatabaseLink
WikigenesACADM
GeneCards"URL":

Protein Aminoacids Percentage

GABAB Receptors

GABAB receptors are metabotropic transmembrane receptors for gamma-aminobutyric acid (GABA) that are linked via G-proteins to potassium channels.

These receptors are found in the central and peripheral autonomic nervous system.

DatabaseLink
WikigenesACADM
GeneCards"URL":

Protein Aminoacids Percentage

GABA vasorelaxation

Hydrogen sulfide as an endogenous modulator in mitochondria and mitochondria dysfunction, 2012

  • It plays a neuromodulatory role in maintaining the balance of excitation and inhibition by a series of ion channel and receptor-mediated effects, which results in upregulation the γ-amino butyric acid (GABA) B receptor (GABABR) and increased K+ conductance.
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