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General Comment |
Gamma-aminobutyric acid (GABA) receptors are a family of proteins involved in the GABAergic neurotransmission of the
mammalian central nervous system. The metabotropic GABA-B receptors are coupled to G proteins and modulate synaptic
transmission through intracellular effector systems. GABA-B receptors function by inhibiting presynaptic transmitter release
or by increasing the potassium conductance responsible for long-lasting inhibitory postsynaptic potentials.
Ng,G.Y.,et al reported the cloning of a novel G-protein-coupled receptor GPR 51 resembling
GABAB receptors expressed predominantly in nervous tissues and
mapped proximal to the hereditary sensory neuropathy type 1 locus
on chromosome 9.
White et al reported that yeast two-hybrid screening showed that this new GABA(B)R2-receptor subtype
forms heterodimers with GABA(B)R1 through an interaction at their intracellular
carboxy-terminal tails. Upon expression with GABA(B)R2 in HEK293T cells,
GABA(B)R1 is terminally glycosylated and expressed at the cell surface.
Co-expression of the two receptors produces a fully functional GABA(B) receptor at
the cell surface; this receptor binds GABA with a high affinity equivalent to that of the
endogenous brain receptor. These results indicate that, in vivo, functional brain
GABA(B) receptors may be heterodimers composed of GABA(B)R1 and
GABA(B)R2.
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