ChemiScreen Recombinant HumanMembrane Preparation

α1A Adrenergic Receptor

Human α1A

The endogenous catecholamines epinephrine and norepinephrine have profound effects on smooth muscle activity, cardiac function, carbohydrate and fat metabolism, hormone secretion, neurotransmitter release, and central nervous system actions. These activities are mediated by GPCRs belonging to two subfamilies, the α- and β-adrenoceptors (Bylund et al., 1994). The three members of the α1 subclass of adrenoceptors, α1A, α1B and α1D, couple to Gq, and promote contraction of vascular and urinary tract smooth muscle, relaxation of intestinal smooth muscle, increased contractile force in the heart, and glycogenolysis and gluconeogenesis in the liver. The different subtypes have overlapping distributions and variably contribute to these effects depending on species and tissue; the α1A subtype plays a prominent role in urogenital smooth muscle contraction and renal artery contraction (Hrometz et al., 1999; Ruffolo and Hieble, 1999). Activation of α1 adrenoceptors also influences cell proliferation; α1A inhibits cell growth by arresting progression at the G1/S transition (Shibata et al., 2003). Chemicon′s α1A 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 α1A interactions with prazosin. The membrane preparations exhibit a Kd of 1.34 nM for [³H]-prazosin. With 5 µg/well α1A Membrane Prep and 1 nM [³H]-prazosin, a greater than 7-fold signal-to-background ratio was obtained.

Radioligand binding assay, and GTPγS binding.

GPCR Class: A

Protein Target: alpha1A

Target Sub-Family: Adrenergic

SPECIFICATIONS: Signal:background and specific binding values obtained in a competition binding assay with varying amounts of α1A membrane prep.

	10 µg/well	5 µg/well
Signal:Background	10.7	9.6
Specific Binding (cpm)	3244	2530

1 unit = 5 µg membrane preparation
Bmax: 11.02 pmol/mg
Kd: 1.34 nM

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 MgCl₂, 1 mM CaCl₂, 0.2% BSA, filtered and stored at 4°C


Radioligand: [3H] prazosin (Perkin Elmer # NET823)


Wash Buffer: 50 mM Hepes, pH 7.4, 500mM NaCl , 0.1% BSA, filtered and stored at 4°C.

One package contains enough membranes for at least 200 assays (units), where an unit is the amount of membrane that will yield greater than 7-fold signal:background with 3H-labeled prazosin at 1 nM. Liquid in packaging buffer: 50 mM Tris pH 7.4, 10% glycerol and 1% BSA with no preservatives. Packaging method: Membranes protein were adjusted to the indicated concentration in packaging buffer, rapidly frozen, and stored at -80°C.

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

CHEMICON is a registered trademark of Merck KGaA, Darmstadt, Germany

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.