Key Specifications Table
| Species | Host Cells | Protein Target |
|---|---|---|
| Human | Chem-1 | GABAB1b |
| Description | |
|---|---|
| Catalogue Number | HTS119M |
| Trade Name |
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| Description | ChemiSCREEN™ Membrane Preparation Recombinant Human GABAB1b/GABAB2 Receptor |
| Overview | Full-length human GABBR1b and GPR51 cDNAs encoding GABAB1b/GABAB2 |
| Background Information | The neurotransmitter γ-aminobutyric acid (GABA) exerts its effects through an ion channel, GABAA, and a GPCR, GABAB. Functional GABAB is a heterodimer composed of the GABAB1 and GABAB2 subunits, which share 35% sequence identity and belong to the class 3 family of GPCRs. The GABAB1 subunit, which exists as splice variants GABAB1a and GABAB1b, binds directly to GABA and is required for agonist activation. The GABAB2 and GABAB1 subunits associate by formation of a coiled coil by their C-terminal tails; this association masks an ER retention sequence in GABAB1 to permit export from the ER and trafficking to the cell surface. In addition to its chaperone function, GABAB2 is the component that couples to Gi to reduce intracellular cAMP. Agonists of GABAB, such as baclofen, are used clinically for treatment of muscle spasticity, migraine headache and musculoskeletal pain (Bowery et al., 2002). Chemicons GABAB1b membrane preparations are crude membrane preparations made from our proprietary stable recombinant cell lines to ensure high-level of GPCR surface expression; thus, they are ideal HTS tools for screening of antagonists of GABAB1b receptor interactions with its ligand. The membrane preparations exhibit a Kd of 1.15nM for [3H]-CGP 54626A. With 5.0 ug/well GABAB1b Membrane Prep and 7.5nM [3H]-CGP 54626A, a greater than 5-fold signal-to-background ratio was obtained. |
| Product Information | |
|---|---|
| Format | Membranes |
| Presentation | Liquid in packaging buffer: 50 mM Tris pH 7.4, 10% glycerol and 1% BSA with no preservatives. Packaging method: Membranes protein was adjusted to the indicated concentration in packaging buffer, rapidly frozen, and stored at -80°C. |
| Quality Level | MQ100 |
| Applications | |
|---|---|
| Application | Human GABAB1b GPCR membrane preparation for Radioligand binding Assays & GTPγS binding. |
| Key Applications |
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| Application Notes | Radioligand binding assay and GTPγS binding |
| Biological Information | |
|---|---|
| Entrez Gene Number |
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| Entrez Gene Summary | Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the mammalian central nervous system. GABA exerts its effects through ionotropic [GABA(A/C)] receptors, to produce fast synaptic inhibition, and metabotropic [GABA(B)] receptors, to produce slow, prolonged inhibitory signals. The GABA(B) receptor consists of a heterodimer of two related 7-transmembrane receptors, GABA(B) receptor 1 and GABA(B) receptor 2. The GABA(B) receptor 1 gene is mapped to chromosome 6p21.3 within the HLA class I region close to the HLA-F gene. Susceptibility loci for multiple sclerosis, epilepsy, and schizophrenia have also been mapped in this region. Alternative splicing of this gene generates 4 transcript variants. |
| Gene Symbol |
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| GPCR Class | C |
| Host Cells | Chem-1 |
| Protein Target | GABAB1b |
| Target Sub-Family | GABAB |
| UniProt Number |
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| UniProt Summary | FUNCTION: SwissProt: Q9UBS5 # Isoform 1E function may be to regulate the availability of functional GABA-B-R1A/GABA-B-R2 heterodimers by competing for GABA-B-R2 dimerization. This could explain the observation that certain small molecule ligands exhibit differential affinity for central versus peripheral sites. COFACTOR: Calcium. Required for high affinity binding to GABA. SIZE: 961 amino acids; 108320 Da SUBUNIT: Heterodimer of GABA-B-R1 and GABA-B-R2. Neither of which is effective on its own and homodimeric assembly does not seem to happen. Isoform 1E (without C-terminal intracellular domain) is unable to dimerize via a coiled-coil interaction with GABA-B-R2. Interacts with the leucine zipper of the C-terminal bZIP domain of ATF4 via its C-terminal region. SUBCELLULAR LOCATION: Cell membrane; Multi-pass membrane protein. Note=Colocalizes with ATF4 in hippocampal neuron dendritic membranes (By similarity). Moreover coexpression of GABA-B-R1 and GABA-B-R2 appears to be a prerequisite for maturation and transport of GABA-B-R1 to the plasma membrane. & Isoform 1E: Secreted (Probable). TISSUE SPECIFICITY: Highly expressed in brain and weakly in heart, small intestine and uterus. Mostly expressed in granular cell and molecular layer for isoform 1A and in Purkinje cells form isoform 1B. Isoform 1E is predominantly expressed in peripheral tissues as kidney, lung, trachea, colon, small intestine, stomach, bone marrow, thymus and mammary gland. DOMAIN: SwissProt: Q9UBS5 Alpha-helical parts of the C-terminal intracellular region mediate heterodimeric interaction with GABA-B receptor 2. The linker region between the transmembrane domain 3 (TM3) and the transmembrane domain 4 (TM4) probably play a role in the specificity for G-protein coupling. SIMILARITY: Belongs to the G-protein coupled receptor 3 family. GABA-B receptor subfamily. & Contains 2 Sushi (CCP/SCR) domains. |
| Incubation Conditions | Membranes are mixed with radioactive ligand and unlabeled competitor (see Figures 1 and 2 for concentrations tested) in binding buffer in a nonbinding 96-well plate, and incubated for 1-2 h. Prior to filtration, an FC 96-well harvest plate (Millipore cat. # MAHF C1H) is coated with 0.33% polyethyleneimine for 30 min, then washed with 50mM Tris, pH 7.4. Binding reaction is transferred to the filter plate, and washed 3 times (1 mL per well per wash) with Wash Buffer. The plate is dried and counted. Binding buffer: 1X Hanks Balanced Salt Solution (HBSS): GIBCO Cat. No. 14175 Radioligand: [3H]-CGP 54626A (American Radiolabeled Chemicals Inc., ART 517) Wash Buffer: 1X Hanks Balanced Salt Solution (HBSS): GIBCO Cat. No. 14175 One package contains enough membranes for at least 200 assays (units), where an unit is the amount of membrane that will yield greater than 5-fold signal:background with 3H-labeled CGP 54626A at 7.5nM. |
| Product Usage Statements |
|---|
| 5 µg/well | |
|---|---|
| Signal:Background | 6.4 |
| Specific Binding (cpm) | 2879 |
SPECIFICATIONS: 1 unit = 5.0 µg membrane preparation
Bmax: 8.49 pmol/mg
Kd: 1.15 nM Usage Statement
- Unless otherwise stated in our catalog or other company documentation accompanying the product(s), our products are intended for research use only and are not to be used for any other purpose, which includes but is not limited to, unauthorized commercial uses, in vitro diagnostic uses, ex vivo or in vivo therapeutic uses or any type of consumption or application to humans or animals.
| Storage and Shipping Information | |
|---|---|
| Storage Conditions | Maintain frozen at -70°C for up to 2 years. Do not freeze and thaw. |
| Packaging Information | |
|---|---|
| Material Size | 200 units |