title: Glycoprotein nature of alpha 2-adrenergic receptors labeled with p-azido[3H] clonidine in calf retina membranes.
abstract: alpha 2-Adrenergic receptors in calf retina membranes can be specifically labeled with the tritiated agonist p-azido[3H]clonidine. Saturation binding in the dark occurs with high affinity (1.3 +/- 0.3 nM) to a single class of sites (1122 +/- 67 fmol/mg protein). Irradiation of the membrane-bound radioligand results in the labeling of a peptide band with an apparent size of 65 kDa and a characteristic pharmacological profile for an alpha 2-adrenergic receptor. The carbohydrate moieties of the alpha 2-receptor are characterized by lectin affinity chromatography and glycosidase treatment. The Nonidet P-40-solubilized, p-azido[3H]clonidine-labeled receptors are completely retained by Con A- as well as WGA-Sepharose columns. Neuraminidase, alpha-mannosidase and TFMS do not affect the electrophoretic mobility of the receptor on SDS-PAGE whereas endoglycosidase F reduces the apparent size to 45 kDa.
authors.affiliation: Department of Protein Chemistry, Vrije Universiteit Brussel, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Convents
authors.forename: J P
authors.initials: JP
authors.lastname: De Backer
authors.forename: E
authors.initials: E
authors.lastname: Van Driessche
authors.forename: D
authors.initials: D
authors.lastname: Convents
authors.forename: S
authors.initials: S
authors.lastname: Beeckmans
authors.forename: G
authors.initials: G
authors.lastname: Vauquelin
mesh_terms: D000345:Affinity Labels / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002846:Chromatography, Affinity; D003000:Clonidine / Q000031:analogs & derivatives* / Q000378:metabolism; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D011942:Receptors, Adrenergic, alpha / Q000302:isolation & purification / Q000378:metabolism*; D012160:Retina / Q000378:metabolism*
chemical_list: D000345:Affinity Labels; D008562:Membrane Glycoproteins; D011942:Receptors, Adrenergic, alpha; C047734:4-azidoclonidine; D003000:Clonidine