Central nervous system
GABA binding (to the “GABA site”) activates the GABA A receptor, allowing chloride ions to flow through the central pore and hyperpolarize the neuron, decreasing the probability that it will propagate an action potential. In this activity, the GABA A receptor does not differ from any other ligand-gated ion channels. However, among neurotransmitter receptors, GABA A receptors are unique in the number of ligands that allosterically modulate receptor function (Olsen et al., 2004).  Less is known about the GABA B receptor, primarily due to the limited number of pharmacological agents selective for this site. Originally, GABA B receptors were identified by their insensitivity to the GABA A antagonist bicuculline and certain GABA A-specific agonists [ 1, 10 ]. GABA B receptors are coupled indirectly to K + channels. When activated, these receptors can decrease Ca 2+ conductance and inhibit cAMP production via intracellular mechanisms mediated by G proteins. GABA B receptors can mediate both postsynaptic and presynaptic inhibition. Properties of GABA receptors. GABA (g-aminobutyric acid) is the main inhibitory neurotransmitter in the central nervous system. The inhibitory action of GABA is mediated by the receptors present on the cell membrane, and results in a reduction of neuronal excitablity. At least three types of GABA receptors have been characterized. Of these LGICs, γ-aminobutyric acid type A (GABA A) receptors appear to occupy a central role in mediating the effects of ethanol in the CNS. GABA is the primary inhibitory neurotransmitter in the mammalian CNS, and activation of GABA A receptors by GABA tends to decrease neuronal excitability.  The active site of the GABA A receptor is the binding site for GABA and several drugs such as muscimol, gaboxadol, and bicuculline. The protein also contains a number of different allosteric binding sites which modulate the activity of the receptor indirectly. Its endogenous ligand is γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Upon activation, the GABA A receptor selectively conducts Cl− through its pore, resulting in hyperpolarization of the neuron. There are two classes of GABA receptors: GABAA and GABAB. GABA A receptors are ligand-gated ion channels (also known as ionotropic receptors), whereas GABA B receptors are G protein-coupled receptors (also known as metabotropic receptors). Fast-responding GABA receptors are members of family of Cys-loop ligand-gated ion channels. Members of this superfamily, which includes nicotinic acetylcholine receptors, GABA A receptors, glycine and 5-HT3 receptors, possess a characteristic loop formed by a disulfide bond between two cysteine residues. GABA receptors have been identified electrophysiologically and pharmacologically in all regions of the brain. Because GABA is widely distributed and utilized throughout the CNS, early GABAergic drugs had very generalized effects on CNS function. GABA B receptors are coupled indirectly to K + channels. When activated, these receptors can decrease Ca 2+ conductance and inhibit cAMP production via intracellular mechanisms mediated by G proteins. GABA B receptors can mediate both postsynaptic and presynaptic inhibition. Schematic structure of the GABA A receptor. Left: GABA A monomeric subunit imbedded in a lipid bilayer (yellow lines connected to blue spheres). The four transmembrane α-helices (1–4) are depicted as cylinders. Its endogenous ligand is γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Upon activation, the GABA A receptor selectively conducts Cl− through its pore, resulting in hyperpolarization of the neuron. GABA(A) Receptors are ionototropic γ-aminobutyric acid type A receptors. Most of the fast inhibitory synaptic transmissions in the brain are mediated by these ligand-gated ion channels in response in to γ-aminobutyric binding.  The GABAA receptor (GABAAR) is an ionotropic receptor and ligand-gated ion channel. Its endogenous ligand is γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Upon activation, the GABA A receptor selectively conducts Cl− through its pore, resulting in hyperpolarization of the neuron.
http://psychology.wikia.com/wiki/GABA_receptor http://www.ncbi.nlm.nih.gov/books/NBK28090/ http://webvision.med.utah.edu/book/part-v-phototransduction-in-rods-and-cones/gabac-receptors-in-the-vertebrate-retina/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC165791/ https://en.wikipedia.org/wiki/GABAA_receptor https://en.wikipedia.org/wiki/GABA_receptor http://www.ncbi.nlm.nih.gov/books/NBK28090/ https://en.wikipedia.org/wiki/GABAA_receptor http://www.alomone.com/i/Antibodies_to_GABA(A)_Receptors/89 https://en.wikipedia.org/wiki/GABAA_receptor
what are gaba receptors for