ISSN:
1573-4919
Keywords:
α1-adrenergic receptor
;
membrane
;
photoaffinity
;
smooth muscle
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Summary In this study, we have used an α1-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 α1-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 α1-adrenergic receptor. Following incorporation of (125I)ADP 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 α1-adrenergic interaction. Prazosin (α1-selective) blocked incorporation of the label into the Mr = 81 000 protein while yohimbine (α2-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 α1-adrenergic receptor resides in a Mr = 81 000 protein.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00220985
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