The GABA-B receptor heterodimer: molecular mechanisms & dependencies

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What it does

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Recorded relationships

What it acts on

Cells heterologously expressing the cloned DNA encoding the GABA-B R1 protein exhibit high-affinity antagonist-binding sites but produce little of the functional activity expected from studies of endogenous GABA-B receptors in the brain, neither GABA-B R1 nor GABA-B R2 when expressed individually activates GIRK-type potassium channels, however the combination of the two confers robust stimulation of channel activity, both genes are co-expressed in individual neurons and both proteins co-localize in transfected cells, and immunoprecipitation indicates that the two polypeptides associate with each other probably as heterodimers.
The GABA-B receptor heterodimer → G-protein-gated inwardly rectifying potassium (GIRK) channels source_derived_draftungraded
Experimental context and source evidence
evidence_span
{"source_cache": "artifacts/gaba-research/9872315.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "c6687fd9eb8b7ebcc0496a2385b0201b02662a5fe8da87a0089650a150f00613", "start_char": 0, "end_char": 1473, "text_sha256": "c6687fd9eb8b7ebcc0496a2385b0201b02662a5fe8da87a0089650a150f00613"}
experimental_model
Heterologous expression and immunoprecipitation of two GABA-B polypeptides with potassium channel readout
exposure
GABA-B R1 and R2 expressed alone and together, with GIRK-type potassium channel activity as the readout
limitations
Heterologous expression. The functional claim rests on channel activation in transfected cells rather than in native tissue.
nutrient_topic
GABA research collection; topical membership is not evidence of a direct clinical effect, and the sign of a GABA response depends on the chloride gradient of the cell it was measured in. · Gamma-aminobutyric acid
organism
Rat and human genes
plain_language
Two proteins that each do almost nothing on their own make a working receptor only when put together.
primary_references
[gb-p9872315] GABA(B) receptors function as a heteromeric assembly of the subunits GABA(B)R1 and GABA(B)R2. (1998). https://pubmed.ncbi.nlm.nih.gov/9872315/ DOI: 10.1038/25348
tissue_or_cell_type
Transfected cells and neurons
GABA: a ligand with no sign of its own, the cofactor that limits its synthesis, the barrier that keeps it out of the brain, and the immune settings where the same molecule protects and harms (2026-09-22) · lines 274–285
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Heterologous expression and immunoprecipitation of two GABA-B polypeptides with potassium channel readout · source_derived_draft · unverified_draft
### gb-neither-half-works-alone Cells heterologously expressing the cloned DNA encoding the GABA-B R1 protein exhibit high-affinity antagonist-binding sites but produce little of the functional activity expected from studies of endogenous GABA-B receptors in the brain, neither GABA-B R1 nor GABA-B R2 when expressed individually activates GIRK-type potassium channels, however the combination of the two confers robust stimulation of channel activity, both genes are co-expressed in individual neurons and both proteins co-localize in transfected cells, and immunoprecipitation indicates that the two polypeptides associate with each other probably as heterodimers. Condition category: normal nutrient_topic: GABA research collection; topical membership is not evidence of a direct clinical effect, and the sign of a GABA response depends on the chloride gradient of the cell it was measured in. plain_language: Two proteins that each do almost nothing on their own make a working receptor only when put together. organism: Rat and human genes tissue_or_cell_type: Transfected cells and neurons experimental_model: Heterologous expression and immunoprecipitation of two GABA-B polypeptides with potassium channel readout limitations: Heterologous expression. The functional claim rests on channel activation in transfected cells rather than in native tissue. exposure: GABA-B R1 and R2 expressed alone and together, with GIRK-type potassium channel activity as the readout evidence_span: {"source_cache": "artifacts/gaba-research/9872315.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "c6687fd9eb8b7ebcc0496a2385b0201b02662a5fe8da87a0089650a150f00613", "start_char": 0, "end_char": 1473, "text_sha256": "c6687fd9eb8b7ebcc0496a2385b0201b02662a5fe8da87a0089650a150f00613"} [gb-p9872315] GABA(B) receptors function as a heteromeric assembly of the subunits GABA(B)R1 and GABA(B)R2. (1998). https://pubmed.ncbi.nlm.nih.gov/9872315/ DOI: 10.1038/25348
Complete structured claim and evidence

Where it participates (unsigned role)

A new GABA-B receptor subtype GABA-B R2 does not bind available GABA-B antagonists with measurable potency, GABA-B R1a, R1b and R2 alone do not activate Kir3-type potassium channels efficiently but co-expression yields a robust coupling to activation of Kir3 channels, there is evidence for assembly of heteromeric GABA-B receptors in vivo with the proteins immunoprecipitating and localizing together at dendritic spines, and the heteromeric receptor complexes exhibit a significant increase in agonist- and partial-agonist-binding potencies as compared with individual receptors and probably represent the predominant native GABA-B receptor.
GABA-B receptor subunit 2 / GABBR2 → GABA-B receptor subunit 1 / GABBR1 source_derived_draftungraded
Experimental context and source evidence
evidence_span
{"source_cache": "artifacts/gaba-research/9872317.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "6a3eefc95d36d31151d094326c5d7f6dedd19b335dee29442de15b4b37ad9cfb", "start_char": 0, "end_char": 1620, "text_sha256": "6a3eefc95d36d31151d094326c5d7f6dedd19b335dee29442de15b4b37ad9cfb"}
experimental_model
Cloning of a second GABA-B subtype with binding potency and Kir3 channel coupling
exposure
GABA-B R1a, R1b and R2 expressed alone and in combination
limitations
A companion study reaching the same conclusion by a different route, including colocalisation at dendritic spines in vivo.
nutrient_topic
GABA research collection; topical membership is not evidence of a direct clinical effect, and the sign of a GABA response depends on the chloride gradient of the cell it was measured in. · Gamma-aminobutyric acid
organism
Rat
plain_language
Put the two subunits together and the receptor not only works but binds its agonist far better than either part did.
primary_references
[gb-p9872317] GABA(B)-receptor subtypes assemble into functional heteromeric complexes. (1998). https://pubmed.ncbi.nlm.nih.gov/9872317/ DOI: 10.1038/25360
tissue_or_cell_type
Transfected cells and dendritic spines
GABA: a ligand with no sign of its own, the cofactor that limits its synthesis, the barrier that keeps it out of the brain, and the immune settings where the same molecule protects and harms (2026-09-22) · lines 287–298
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Cloning of a second GABA-B subtype with binding potency and Kir3 channel coupling · source_derived_draft · unverified_draft
### gb-the-pair-binds-better-than-either A new GABA-B receptor subtype GABA-B R2 does not bind available GABA-B antagonists with measurable potency, GABA-B R1a, R1b and R2 alone do not activate Kir3-type potassium channels efficiently but co-expression yields a robust coupling to activation of Kir3 channels, there is evidence for assembly of heteromeric GABA-B receptors in vivo with the proteins immunoprecipitating and localizing together at dendritic spines, and the heteromeric receptor complexes exhibit a significant increase in agonist- and partial-agonist-binding potencies as compared with individual receptors and probably represent the predominant native GABA-B receptor. Condition category: normal nutrient_topic: GABA research collection; topical membership is not evidence of a direct clinical effect, and the sign of a GABA response depends on the chloride gradient of the cell it was measured in. plain_language: Put the two subunits together and the receptor not only works but binds its agonist far better than either part did. organism: Rat tissue_or_cell_type: Transfected cells and dendritic spines experimental_model: Cloning of a second GABA-B subtype with binding potency and Kir3 channel coupling limitations: A companion study reaching the same conclusion by a different route, including colocalisation at dendritic spines in vivo. exposure: GABA-B R1a, R1b and R2 expressed alone and in combination evidence_span: {"source_cache": "artifacts/gaba-research/9872317.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "6a3eefc95d36d31151d094326c5d7f6dedd19b335dee29442de15b4b37ad9cfb", "start_char": 0, "end_char": 1620, "text_sha256": "6a3eefc95d36d31151d094326c5d7f6dedd19b335dee29442de15b4b37ad9cfb"} [gb-p9872317] GABA(B)-receptor subtypes assemble into functional heteromeric complexes. (1998). https://pubmed.ncbi.nlm.nih.gov/9872317/ DOI: 10.1038/25360
Complete structured claim and evidence

The events it takes part in

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In the sources

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Open hypotheses

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The GABA-B receptor heterodimer