Photoaffinity labeling of the beta-adrenergic receptor from cultured lymphoma cells with [125I]iodoazidobenzylpindolol: loss of the label with desensitization.

Abstract

The beta-adrenergic antagonist [125I]iodoazidobenzylpindolol ( [125I]IABP) specifically photolabeled two polypeptides in membrane preparations from wild-type (WT) and coupling protein-deficient cyc- cultured lymphoma cells. The molecular weights of the two polypeptides determined by sodium dodecyl sulfate/polyacrylamide gel electrophoresis were 65,000 and 55,000. They were labeled in a ratio of approximately 1:1. Pretreatment of intact WT or cyc- cells with 1.0 microM epinephrine for 15 min (desensitization) resulted in a greater loss of the 55,000 Mr polypeptide (40-60%) relative to the 65,000 Mr peptide (10-30% loss). An 18- to 24-hr pretreatment of WT cells with terbutaline (down-regulation) led to a greater than 90% reduction of the photolabeling of both polypeptides, whereas a similar pretreatment of cyc- cells resulted in no further loss of labeled receptor than that observed after only a 15-min pretreatment with epinephrine. There was no indication of a change in the electrophoretic mobility of the [125I]IABP-labeled receptors after either short- or long-term agonist pretreatment. These data provide direct evidence for heterogeneity of the beta-adrenergic receptor in lymphoma cells. The differential loss of the [125I]IABP labeling in the two polypeptides suggests a functional heterogeneity as well.

• Authors: A Rashidbaigi, A E Ruoho, D A Green, R B Clark
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 80 Issue 10 Pg. 2849-53 (May 1983) ISSN: 0027-8424 [Print] United States
• PMID: 6134281 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Adrenergic beta-Agonists
• Affinity Labels
• Azides
• Receptors, Adrenergic
• Receptors, Adrenergic, beta
• 1-(indol-4-yloxy)-3-(1-(4-azido-3-iodophenyl)-2-isobutylamine)-2-propanol
• Pindolol
• Adenylyl Cyclases

Topics

• Adenylyl Cyclases (metabolism)
• Adrenergic beta-Agonists (pharmacology)
• Affinity Labels
• Animals
• Azides
• Cells, Cultured
• Lymphoma (metabolism)
• Mice
• Molecular Weight
• Pindolol (analogs & derivatives)
• Receptors, Adrenergic (metabolism)
• Receptors, Adrenergic, beta (drug effects, metabolism)
• Time Factors