MOLECULAR CHARACTERIZATION OF A RAT ALPHA-2B-ADRENERGIC RECEPTOR

α2-Adrenergic receptors comprise a hetero-geneous population based on pharmacologic and molecular evidence. We have isolated a cDNA clone (pRNGα2) encoding a rat α2-adrenergic receptor. A rat kidney cDNA library was screened with an oligonucleotide complementary to a highly conserved region found in all biogenic amine receptors described to date. The deduced amino acid sequence displays many features of guanyl nucleotide-binding protein-coupled receptors except it does not have a consensus N-linked glycosylation site near the amino terminus. Membranes prepared from COS cells transfected with pRNGα2 DNA display high affinity and saturable binding to [3H]rauwolscine (Kd = 2 nM). Competition curve data analysis shows that RNGα2 protein binds to a variety of adrenergic drugs with the following rank order of potency: yohimbine ≥ chlorpromazine > prazosin ≥ clonidine > norepinephrine ≥ oxymetazoline. RNGα2 RNA accumulates in both rat kidney and neonatal rat lung (predominant species is 4000 nucleotides). When a cysteine residue (Cys-169) that is conserved among all members of the seven-transmembrane-region superfamily is changed to phenylalanine, the RNGα2 protein fails to bind [3H]rauwolscine after expression in COS cells. We conclude that pRNGα2 likely represents a cDNA for a rat α2B-adrenergic receptor.