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GABA (gamma-amino butyric acid) is the most abundant neurotransmitter in mammalian brain. GABA, like other neurotransmitters, including L-glutamate, serotonin, and acetylcholine, activates both ionotropic and metabotropic receptors. The ionotropic receptors are ligand gated ion channels that convey fast synaptic transmission. In contrast, G-protein coupled metabotropic receptors modulate synaptic transmission through intracellular effector systems. The metabotropic receptors for L-glutamate (mGluRs) differ structurally from other G-coupled receptors with 7 TM domains. GABA exerts its effects through ionotropic ligand-gated GABAA, GABAC and GABAB to produce slow, and prolonged synaptic inhibitory signals by activating a Cl- conductance that is allosterically modulated by many psychoactive drugs, such as the benzodiazepines, barbiturates and neurosteroids.

The subunits composition of GABAA, receptor has sequence homology with nAChR subunit family, and the two families have presumably diverged from a common ancestral gene. A family of GABA-A receptors subtypes exists, which are generated by alternative splicing of alpha 1-6, beta 1-4, gamma 1-4, delta, epsilon, pie, theta, and rho1-3 to form a heteromeric (pentameric?) protein complexes. Various

GABA-A subunits show distinct patterns of temporal and spatial expression that may imply its tissue specific physiological role (1). GABA A (GAA) receptor proteins (450-627 aa) are characterized by the presence of a cleavable signal peptide, a large extracellular N-terminus, 3 TM (transmembrane) domains, a large cytoplasmic domain followed by TM4 and C-terminal extracellular domain. The other common motif is so-called Cys-loop, two Cys separated by 13 aa, in the extracellular domain. The regions between TM3-4 and the large cytoplasmic loop are least conserved among various GAA subunits, which may confer subunit specific functionality. GAA genes are distributed as clusters throughout the human genome (chromosomes 4, 5, 15, and X; delta subunit on chromosome 1).

Most recently, a new cellular protein, termed GABAA, receptor associated protein (GABARAP), has bee shown to interact with gamma 2 subunit of GAA. GABARAP has similarity with light chain-3 microtubule associated protein 1A and 1B. N-terminus of GABARAP also possesses a tubulin-binding motif. Therefore, a possible interaction of GAA, GABARAP, and tubulin suggest for the targeting and clustering of GAA. GABARAP is found in brain and most other tissues.
 

m=mouse; r=rat; h=human; b=bovine; c=chicken; d=dog; ~CT or ~NT=near C or N-terminus. EC=Extracellular; CL=Cytoplasmic loop;

* Expected antibody crossreactivity information is mostly based upon high (>70%) sequence conservation of antigenic/control peptides in various species. When antibody crossreactivity has actually been experimentally confirmed in various species, it will be mentioned in the appropriate data sheets.

"Neat Antisera or antisera" are the unpurified antiserum and it is suitable for ELISA and Western.
"Affinity pure" IgG may be more suitable for immunohistochemical (IHC) applications and to reduce background in most immunological applications including ELISA and Western.
"Control peptides" can not be used for Western as they are very short peptides. They are intended for ELISA or antibody blocking studies to establish antibody specificity.
Western blot +ve protein controls, where available, are semi-pure, pure or recombinant proteins that are formulated in SDS-PAGE sample buffer. They are recommended to be used for Western (load 10 ul/lane) for visualisation with antibodies.

Antibodies to various GABA Transporters (GAT1-3), GABA, & GABA B receptors are also available.

 

© 2005 GENTAUR bvba
 

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