gamma-aminobutyric acid type B receptor subunit 2; GABA-B receptor 2; GABA-B-R2; GABA-BR2; GABABR2; Gb2; G-protein coupled receptor 51; HG20 (GABBR2, GPR51, GPRC3B)
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Function
- receptor for GABA
- activity is mediated by G-proteins that
- inhibit adenylyl cyclase activity
- stimulate phospholipase A2
- activate K+ channels
- inactivate voltage-dependent Ca+2-channels
- modulate inositol phospholipid hydrolysis
- role in fine-tuning of inhibitory synaptic transmission
- pre-synaptic GABA-B-R inhibits neurotransmitter release by down-regulating high- voltage activated Ca+2 channels
- postsynaptic GABA-B-R decreases neuronal excitability by activating a prominent inwardly rectifying K+ channel (Kir conductance) that underlies the late inhibitory postsynaptic potentials
- implicated in:
- synaptic inhibition
- hippocampal long-term potentiation
- slow wave sleep
- muscle relaxation
- antinociception
- heterodimer of GABA-B-R1 & GABA-B-R2, neither of which is effective on its own & homodimeric assembly does not seem to happen
- interacts with ATF4 via its C-terminal region
Structure
- alpha-helical parts of the C-terminal intracellular region mediate heterodimeric interaction with GABA-B receptor 1
- belongs to the G-protein coupled receptor 3 family GABA-B receptor subfamily
Compartment
- cell membrane; multi-pass membrane protein
- cell junction, synapse, postsynaptic cell membrane
- coexpression of GABA-B-R1 & GABA-B-R2 appears to be requeired for maturation & transport of GABA-B-R1 to the plasma membrane
Expression
- highly expressed in brain, especially in cerebral cortex, thalamus, hippocampus, frontal, occipital & temporal lobe, occipital pole & cerebellum
- lesse expression in corpus callosum, caudate nucleus, spinal cord, amygdala & medulla
- weakly expressed in heart, testis & skeletal muscle