ChemiScreen Membrane Preparation
Recombinant Human M5 Muscarinic Acetylcholine Receptor

Full-length human CHRM5 cDNA, encoding M5

The muscarinic acetylcholine receptor family consists of five GPCRs that mediate some of the neurotransmission functions of acetylcholine in the CNS and the periphery. The M5 receptor, along with the M1 and M3 receptors, signal through Gq/11 and subsequent release of Ca++ from the ER (Caulfield and Birdsall, 1998). Although M5 is expressed in the CNS at relatively low levels, it appears to be the only muscarinic acetylcholine receptor expressed in midbrain dopaminergic neurons, and it has been shown to mediate dopamine release from these neurons. The M5 receptor is also expressed in blood vessels in the brain and the periphery, and studies with M5 knockout mice demonstrate that M5 mediates the vasodilatory action of acetylcholine on cerebral microvessels. Further studies with M5 knockout mice also indicate a role for M5 in the rewarding effects of cocaine and morphine (Wess, 2004). Chemicon′s M5 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 M5 interactions with its ligands. The membrane preparations exhibit a Kd of 0.16 nM for [³H]-Scopolamine methyl chloride (NMS). With 10 μg/well M5 Membrane Prep and 1 nM [³H]-NMS, greater than 5-fold signal-to-background ratio was obtained.

Radioligand binding assay and GTPγS binding.

GPCR Class: A

Protein Target: M5

Target Sub-Family: Acetylcholine (muscarinic)

Bmax: 2.49 pmol/mg; Kd: 0.16nM
1 unit = 10 μg

Inucbation 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, a GF/C 96-well filter plate is coated with 0.33% polyethyleneimine for 30 min, then washed with 50mM HEPES, pH 7.4, 0.5% BSA. 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: 50 mM Hepes, pH 7.4, 5 mM MgCl_{2, 1 mM CaCl2, 0.2% BSA, filtered and stored at 4°C Radioligand: [3H] NMS (Perkin Elmer#:NEX-636 )
Wash Buffer: 50 mM Hepes, pH 7.4, 500 mM NaCl , 0.1% BSA, filtered and stored at 4°C.
One package contains enough membranes for at least 200 assays (units), where a unit is the amount of membrane that will yield greater than 5-fold signal:background with 3H-labeled NMS at 1 nM}

Liquid in packaging buffer: 50 mM Tris pH 7.4, 10% glycerol and 1% BSA no preservatives. Packaging method: Membranes protein were adjusted to 0.5 mg/mL in 1 mL packaging buffer, rapidly frozen, and stored at -80&degC.

Maintain frozen at -70°C for up to 2 years. Do not freeze and thaw.

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