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Journal of Biomedical Optics

Terbutaline causes immobilization of single β2-adrenergic receptor-ligand complexes in the plasma membrane of living A549 cells as revealed by single-molecule microscopy
Author(s): Anne Sieben; Tim P. Kaminski; Hanns Haberlein; Ulrich Kubitscheck
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Paper Abstract

G-protein-coupled receptors are important targets for various drugs. After signal transduction, regulatory processes, such as receptor desensitization and internalization, change the lateral receptor mobility. In order to study the lateral diffusion of β2-adrenergic receptors (β2AR) complexed with fluorescently labeled noradrenaline (Alexa-NA) in plasma membranes of A549 cells, trajectories of single receptor-ligand complexes were monitored using single-particle tracking. We found that a fraction of 18% of all β2ARs are constitutively immobile. About 2/3 of the β2ARs moved with a diffusion constant of D2 = 0.03±0.001 μm2/s and about 17% were diffusing five-fold faster (D3 = 0.15±0.02 μm2/s). The mobile receptors moved within restricted domains and also showed a discontinuous diffusion behavior. Analysis of the trajectory lengths revealed two different binding durations with τ1 = 77±1 ms and τ2 = 388±11 ms. Agonistic stimulation of the β2AR-Alexa-NA complexes with 1 μM terbutaline caused immobilization of almost 50% of the receptors within 35 min. Simultaneously, the mean area covered by the mobile receptors decreased significantly. Thus, we demonstrated that agonistic stimulation followed by cell regulatory processes results in a change in β2AR mobility suggesting that different receptor dynamics characterize different receptor states.

Paper Details

Date Published: 1 February 2011
PDF: 10 pages
J. Biomed. Opt. 16(2) 026013 doi: 10.1117/1.3540670
Published in: Journal of Biomedical Optics Volume 16, Issue 2
Show Author Affiliations
Anne Sieben, Rheinische Friedrich-Wilhelms-Univ. Bonn (Germany)
Tim P. Kaminski, Rheinische Friedrich-Wilhelms-Univ. Bonn (Germany)
Hanns Haberlein, Rheinische Friedrich-Wilhelms-Univ. Bonn (Germany)
Ulrich Kubitscheck, Rheinische Friedrich-Wilhelms-Univ. Bonn (Germany)

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