GABAA Receptor Alpha 1 Beta 2 Gamma 2

Family:
GABA Receptors (Cys-loop ligand-gated ion channels)

Subgroups:
The GABA receptor family has further been divided into GABA_A, GABA_B and GABA_A-ρ (also called GABA_C) receptors.

Topology:
As typical for Cys-loop receptors, generally four transmembrane spanning domains TM1-TM4 form one receptor subunit, five or four subunits form a pore, several heteromeric combinations are known.
GABA_A: Oligomerization of typically five subunits, heteromeric combinations are known of α subunits (GABRA1 - GABRA6), β subunits (GABRB1 - GABRB3) and γ subunits (GABRG1 - GABRG3), as well as δ (GABRD), an ε (GABRE), a π (GABRP), and a θ (GABRQ). The most common type is (α1)₂(β2)₂(γ2), minimal requirement is the inclusion of α and β subunits.
GABA_B: Heterodimer (GABBR1, GABBR2)
GABA_A-ρ: Oligomerization of five subunits, heteromeric combinations of three GABA_A-ρ subunits are known (GABRR1, GABRR2, GABRR3)

Regulation and Function:
GABA_A and GABA_A-ρ receptors are ligand-gated ion channels (ionotropic receptors); whereas GABA_B receptors are G protein-coupled receptors (metabotropic receptors). All respond to the neurotransmitter gamma-aminobutyric acid (GABA), the main inhibitory transmitter in the mammalian CNS.

Data and Applications

GABAA Receptor (α1β2γ2) - Success Rates

SyncroPatch 384PE (a predecessor model of SyncroPatch 384i) data and applications:
Cells were kindly provided by Bsys.

Statistic of hGABA_A α₁β₂γ₂ cells recorded on one NPC-384 1-hole (1x) patch clamp chip. 57 % of the cells on one NPC-384 chip had seal resistance > 1 GOhm at the beginning and 48% at the end of the experiment. Access (RSeries) was good with 80% of cells with RSeries <20 MOhm at the start of the experiment.

GABAA Receptor (a1b2g2) - Stable Responses on Repeated Compound Addition

SyncroPatch 96 (a predecessor model of SyncroPatch 384PE) data and applications:

The traces show repeated application of 100 µM GABA to GABA_A receptors (α1 β2 γ2) expressed in HEK 293 cells. Current amplitudes were stable over time, illustrating the reliable and fast solution excahnge supported by the SyncroPatch 96.

GABAA Receptor (a1b2g2) - Reliable Compound Application

Port-a-Patch data and applications:

Ligand dependent activation of GABA_A receptors can be recorded with the Laminar Flow Chamber with approx. 100 ms time constant for 10 μM GABA. Concentration dependent activation and desensitization of GABA_A (α1β2γ2) receptors was obtained by applying 1, 3 and 10 μM GABA for 2.5 s at a time interval of 20 s.

GABAA Receptor (a1b2g2) - Activation

Patchliner data and applications:

Shown is concentration dependent activation of GABA_A (α1β2γ2) receptors. Shown is the average concentration response curve for an average of 7 cells and the example traces from one cell.

Application Notes

GABAA (a1b2g2) - "Rapid agonist applications in precise intervals (GABAA) "

Patchliner application note: (1.5 MB)

preview the file here for download

GABAA (a1b2g2) - "Patchliner - Investigating the pharmacology of GABAA receptors expressed in HEK293 cells"

Patchliner application note: (0.7 MB)

preview the file here for download

Publications

2016 - Automated Patch Clamp Meets High-Throughput Screening: 384 Cells Recorded in Parallel on a Planar Patch Clamp Module

SyncroPatch 384PE (a predecessor model of SyncroPatch 384i) publication in Journal of Lab Automation (2016)

Authors:
Obergrussberger A., Brüggemann A., Goetze T.A., Rapedius M., Haarmann C., Rinke I., Becker N., Oka T., Ohtsuki A., Stengel T., Vogel M., Steindl J., Mueller M., Stiehler J., George M., Fertig N.

2011 - State-of-the-art automated patch clamp devices: heat activation, action potentials, and high throughput in ion channel screening

Port-a-Patch, Patchliner and SyncroPatch 96 (a predecessor model of SyncroPatch 384PE) publication in Frontiers in Pharmacology (2011)

Authors:
Stoelzle S., Obergrussberger A., Brüggemann A., Haarmann C., George M., Kettenhofen R., Fertig N.

GABAA: Further Readings

GABAA receptors - Investigation of Modulators

Patchliner data and applications:
Cells were kindly provided by AstraZeneca.

The top images show dose dependent block of GABA_A currents by bicuculline. The IC₅₀ was determined as 1.2 ± 0.2 μM (n=11). The lower graph shows the positive modulation of glycine activation of hGlyRα1. Here, six co-applications of 20 μM glycine and increasing concentrations of a positive modulator are shown.

GABAA Receptor - Stacked Application Technology

Patchliner data and applications:

Ligand gated ion channels often display receptor desensitization. A method was developed to minimize ligand exposure times and intervals between ligand exposures. The pipette first aspirates buffer, then compound. When expelling this stack, the cell is first exposed to ligand and then buffer. Exposure times as low as 400 ms are possible with this method. A GABA dose response curve, aquired in this manner, is shown on the left.

GABAA Receptor - Modulator Diazepam

SyncroPatch 96 (a predecessor model of SyncroPatch 384PE) data and applications:

Shown is a raw current response of a HEK293 cell expressing GABA_A receptors to initial exposure to GABA, followed by joint exposure to GABA and diazepam (as indicated). Solutions were stacked (layered) in the pipette to achieve brief exposure times.

GABAA Receptor - Dose Response Curves

SyncroPatch 96 (a predecessor model of SyncroPatch 384PE) data and applications:

Increasing concentrations of GABA were applied to each cell. Cells were from frozen stocks and were prepared for a FliPR experiment running alongside.
The corresponding online analysis of this experiment is shown in the data set "GABAA - CRC Analysis".

GABAA Receptor - Currents in iCell Neurons

Patchliner data and applications:
Cells were kindly provided by Cellular Dynamics.

Activation of GABA_A receptor currents by 30 μM GABA and partial block of the current response by 1 μM bicuculline. Bicuculline was pre-applied for at least 30 s before co-application with GABA (30 μM). Approximately 50% of the current was blocked by 1 μM bicuculline.

GABAA Receptor - CRC Analysis

SyncroPatch 96 (a predecessor model of SyncroPatch 384PE) data and applications:

Online analysis results of the dose response curves were obtained with a few mouse clicks. The color code of the online analysis helps to visualize different concentrations applied.

The corresponding data traces is shown in the data set "GABAA - Dose Response Curves".

2021 - Cell engineering method using fluorogenic oligonucleotide signaling probes and flow cytometry

Patchliner publication in Biotechnology Letters (2021)

Authors:
Shekdar K., Langer J., Venkatachalan S., Schmid L., Anobile J., Shah P., Lancaster A., Babich O., Dedova O., Sawchuck D.

2020 - Novel Expression of GABAA Receptors on Resistance Arteries That Modulate Myogenic Tone

SyncroPatch 96 (a predecessor model of the SyncroPatch 384i) Publication in Journal of Vascular Research (2020)

Authors:
Yim P.D., Gallos G., Lee-Kong S.A., Dan W., Wu A.D., Xu D., Berkowitz D.E., Emala C.W.

2016 - Automated Patch Clamp Meets High-Throughput Screening: 384 Cells Recorded in Parallel on a Planar Patch Clamp Module

SyncroPatch 384PE (a predecessor model of SyncroPatch 384i) publication in Journal of Lab Automation (2016)

GABA_A a1b2g2