title: Glycoprotein nature of D2 dopamine receptors.
abstract: The glycoprotein nature of the ligand binding subunit of photoaffinity-labeled striatal D2 receptors was investigated. Upon photolysis, [125I]N-azidophenethylspiperone covalently incorporated into a major band of Mr 94000 with an appropriate pharmacological profile for D2 receptors as assessed by autoradiography following SDS-polyacrylamide gel electrophoresis. The exoglycosidase, neuraminidase, altered the electrophoretic mobility of the 94 kDa labeled band to 54 kDa with a slight modification in the binding affinity of [3H]spiperone. Endoglycosidase treatment (glycopeptidase-F) produced a further increase in the mobility of the 94 kDa peptide to approximately 43 kDa. A smaller specifically photolabeled D2 receptor peptide of 34 kDa does not contain terminal sialic acid but is an N-linked glycoprotein as assessed by lectin affinity chromatography and susceptibility to digestion by glycopeptidase-F to a peptide of approximately 23 kDa.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism*; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D008562:Membrane Glycoproteins / Q000302:isolation & purification* / Q000378:metabolism; D008970:Molecular Weight; D011954:Receptors, Dopamine / Q000302:isolation & purification* / Q000378:metabolism; D017448:Receptors, Dopamine D2; D013134:Spiperone / Q000378:metabolism
chemical_list: D008562:Membrane Glycoproteins; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D013134:Spiperone