title: Cloning, expression, and pharmacological characterization of a human alpha 2B-adrenergic receptor.
abstract: An alpha 2-adrenergic receptor subtype has been isolated from a human genomic spleen library using the human 5-hydroxytryptamine1A receptor gene (also known as G-21) as a probe. This adrenergic receptor gene encodes a protein of 450 amino acids and does not contain any consensus sequences for N-linked glycosylation in its amino terminus or extracellular loops. This receptor is also distinguished by the presence of 12 consecutive glutamic acid residues in the region of its third intracellular loop. The deduced amino acid sequence shows greatest homology to previously cloned human alpha 2-adrenergic receptors and has structural similarities to other guanine nucleotide-binding protein-coupled receptors. The DNA encoding the human alpha 2 receptor was stably transfected into mouse fibroblast Ltk- cells and radioligand binding studies were performed using the alpha 2 antagonist [3H]rauwolscine. [3H]Rauwolscine bound with high affinity (Kd = 0.33 nM) and in a saturable manner (Bmax = 1.4 pmol/mg of protein). Pharmacological characterization of this receptor indicated a rank order of potency of yohimbine greater than prazosin greater than oxymetazoline. Additionally, 100 microM 5'-guanylylimidodiphosphate, produced a rightward shift in the epinephrine competition curve, with resultant increases in both the Ki value and Hill coefficient, suggestive of a functional interaction of the cloned receptor with native guanine nucleotide-binding protein(s) of Ltk- membranes. The data presented here are consistent with previous biochemical and pharmacological studies on alpha 2 receptors and are supportive of the designation of this receptor as an alpha 2B subtype.
authors.affiliation: Neurogenetic Corporation, Paramus, New Jersey 07652.
authors.forename: R L
authors.initials: RL
authors.lastname: Weinshank
authors.forename: J M
authors.initials: JM
authors.lastname: Zgombick
authors.forename: M
authors.initials: M
authors.lastname: Macchi
authors.forename: N
authors.initials: N
authors.lastname: Adham
authors.forename: H
authors.initials: H
authors.lastname: Lichtblau
authors.forename: T A
authors.initials: TA
authors.lastname: Branchek
authors.forename: P R
authors.initials: PR
authors.lastname: Hartig
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D015870:Gene Expression; D006031:Glycosylation; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D006801:Humans; D008969:Molecular Sequence Data; D011869:Radioligand Assay; D011942:Receptors, Adrenergic, alpha / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis*; D015183:Restriction Mapping; D014162:Transfection; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D011942:Receptors, Adrenergic, alpha; D011994:Recombinant Proteins; D015016:Yohimbine; D006165:Guanylyl Imidodiphosphate