Alpha 1- and beta 2-adrenergic receptors co-expressed on cloned MDCK cells are distinct glycoproteins.
We have explored the molecular differences between alpha 1- and beta 2-adrenergic receptors that are co-expressed by a clonally-derived cell line, Madin-Darby canine kidney clone D (MDCK-D). MDCK-D membranes were pre-labeled with selective alpha 1- and beta-adrenergic radioligands and were then solubilized with the non-ionic detergent digitonin. Solubilized alpha 1- and beta 2-adrenergic receptors were retained by immobilized wheat germ agglutinin and were eluted following addition of N-acetyl-D-glucosamine or sialic acid. Both receptors were also retained by immobilized Limax flavus lectin, a sialic acid-binding lectin. Lectins that were specific for N-acetyl-D-glucosamine residues did not bind to these receptors. These results indicate that both alpha 1 and beta 2 receptors are sialylated glycoproteins. The solubilized alpha 1- and beta 2-adrenergic receptors migrated with different elution profiles from an Ultragel AcA 34 column. The apparent molecular sizes of the digitonin-receptor complexes were 68A for the alpha 1 receptor and 55A for the beta 2 receptor. These results show that alpha 1- and beta 2-adrenergic receptors can be present on the same cell as distinct sialic acid-containing glycoproteins.
D000818:Animals; D002460:Cell Line; D002846:Chromatography, Affinity; D003001:Cloning, Molecular; D004285:Dogs; D006023:Glycoproteins / Q000235:genetics* / Q000302:isolation & purification; D007668:Kidney; D037102:Lectins; D008970:Molecular Weight; D011942:Receptors, Adrenergic, alpha / Q000235:genetics* / Q000302:isolation & purification; D011943:Receptors, Adrenergic, beta / Q000235:genetics* / Q000302:isolation & purification; D012794:Sialic Acids / Q000032:analysis
D006023:Glycoproteins; D037102:Lectins; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D012794:Sialic Acids