ChemiScreen Recombinant Human Glucagon Receptor Membrane Preparation

TRANSFECTION: Full-length human GCGR cDNA encoding Glucagon Receptor
HOST CELLS: Chem-1, an adherent mammalian cell line with no endogenous glucagon receptor expression.

Glucagon is a 29-amino acid peptide that stimulates glycogenolysis and gluconeogenesis in the liver to increase blood glucose. The receptor for glucagon is a class 2 (or class B) GPCR that signals through G_s to stimulate cAMP production (Mayo et al., 2003). Mice lacking the glucagon receptor have mild hypoglycemia after fasting, and exhibit hyperplasia of pancreatic α-cells (Gelling et al., 2003). Because of its role in promoting hyperglycemia, the glucagon receptor presents a potential target for treatment of diabetes. Chemicon′s glucagon receptor 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 glucagon receptor interactions and its ligands. The membrane preparations exhibit a Kd of 3.09 nM for [¹²⁵I]-glucagon. With 1 nM [¹²⁵I]-glucagon, 5 or 10 μg/well glucagon receptor Membrane Prep yields greater than 10-fold signal-to-background ratio.

Inucbation Conditions
RECOMMENDED ASSAY CONDITIONS: Membranes are mixed with radioactive ligand and unlabeled competitor 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: [¹²⁵I]-glucagon (Perkin Elmer#:NEX-207)
• 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 a unit is the amount of membrane that will yield greater than 10-fold signal:background with [¹²⁵I]-labeled glucagon at 1 nM

Liquid in packaging buffer: 50 mM Tris pH 7.4, 10% glycerol and 1% BSA; no preservatives.
Packaging method: Membrane proteins were adjusted to 0.5 mg/ml in 1 ml packaging buffer, rapidly frozen, and stored at -80°C.

SPECIFICATIONS:
1 unit = 5 μg
B_max for [¹²⁵I] glucagon binding: 16.7 pmol/mg protein
K_d for [¹²⁵I] glucagon binding: ~ 3.09 nM

Signal:background and specific binding values obtained in a competition binding assay with varying amounts of Glucagon receptor membrane prep:

	10 µg/well	5 µg/well
Signal:Background	10.1	35
Specific Binding (cpm)	33315	36252

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