Ribonuclease Protection Assay for the Detection of β1-Adrenergic Receptor RNA

The β-ARs are members of a large family of neurotransmitter receptors, which interact with GTP binding proteins (G-proteins) to modulate second messenger systems (1 ,2 ). The β-ARs mediate the physiological effects of the catecholamines epinephrine and norepinephrine; when ligand-activated, these receptors initiate the production of cyclic AMP. Three subtypes of β-ARs, β₁ -AR, β₂ -AR, and β₃ -AR, have been identified on the basis of their pharmacological properties, physiological effects, tissue and cell-type specificity, and genetic structure (1 –2 ). All three β-AR subtypes have conserved structural features, including hydrophobicity profiles consistent with seven-transmembrane domains, sites of N-linked glycosylation near the amino-terminus, potential phosphorylation sites for protein kinases in presumed cytoplasmic domains, and highly conserved amino acid similarity within the transmembrane domains.