Photoaffinity labeling of the DDT1 MF-2 cell alpha 1-adrenergic receptor

Mol Cell Biochem. 1985 May;67(1):47-53. doi: 10.1007/BF00220985.


In this study, we have used an alpha 1-adrenergic receptor photoaffinity ligand, 2-[4-(4-azido-3-iodo-benzoyl)-piperazin-1-yl]-4-amino-6, 7-dimethoxyquinazoline (125I-APD), to label covalently the alpha 1-adrenergic receptor in a smooth muscle cell line. Our results indicate that in the absence of light, (125I)APD binds reversibly to a site in the DDT1 MF-2 cell membranes having pharmacological characteristics of an alpha 1-adrenergic receptor. Following incorporation of (125I)APD into partially purified membranes a single labeled band of protein with a Mr of 81 000 was visualized by autoradiography following sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Incorporation of (125I)-APD into this band was affected by adrenergic agonists and antagonists in a manner consistent with an alpha 1-adrenergic interaction. Prazosin (alpha 1-selective) blocked incorporation of the label into the Mr = 81 000 protein while yohimbine (alpha 2-selective) did not. Of the adrenergic agonists, (-)-epinephrine and (-)-norepinephrine but not (-)-isoproterenol blocked labeling of the Mr = 81 000 protein. We conclude that the ligand binding site of the DDT1 MF-2 cell alpha 1-adrenergic receptor resides in a Mr = 81 000 protein.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adrenergic alpha-Agonists / pharmacology
  • Adrenergic alpha-Antagonists / pharmacology
  • Affinity Labels
  • Animals
  • Azides
  • Cell Line
  • Muscle, Smooth / analysis*
  • Photochemistry
  • Prazosin / analogs & derivatives
  • Prazosin / pharmacology
  • Quinazolines
  • Receptors, Adrenergic, alpha / analysis*
  • Receptors, Adrenergic, alpha / drug effects
  • Yohimbine / pharmacology


  • Adrenergic alpha-Agonists
  • Adrenergic alpha-Antagonists
  • Affinity Labels
  • Azides
  • Quinazolines
  • Receptors, Adrenergic, alpha
  • Yohimbine
  • azidoprazosin
  • Prazosin