Plasmon-waveguide resonance studies of ligand binding to the human beta 2-adrenergic receptor.
Plasmon-waveguide resonance (PWR) spectroscopy is an optical technique that can be used to probe the molecular interactions occurring within anisotropic proteolipid membranes in real time without requiring molecular labeling. This method directly monitors mass density, conformation, and molecular orientation changes occurring in such systems and allows determination of protein-ligand binding constants and binding kinetics. In the present study, PWR has been used to monitor the incorporation of the human beta(2)-adrenergic receptor into a solid-supported egg phosphatidylcholine lipid bilayer and to follow the binding of full agonists (isoproterenol, epinephrine), a partial agonist (dobutamine), an antagonist (alprenolol), and an inverse agonist (ICI-118,551) to the receptor. The combination of differences in binding kinetics and the PWR spectral changes point to the occurrence of multiple conformations that are characteristic of the type of ligand, reflecting differences in the receptor structural states produced by the binding process. These results provide new evidence for the conformational heterogeneity of the liganded states formed by the beta(2)-adrenergic receptor.
Devanathan
Savitha
S
Department of Biochemistry and Molecular Biophysics, University of Arizona, Tucson, Arizona 85721, USA.
Yao
Zhiping
Z
Salamon
Zdzislaw
Z
Kobilka
Brian
B
Tollin
Gordon
G
D000322:Adrenergic Agonists / Q000737:chemistry; D058666:Adrenergic beta-2 Receptor Agonists; D058672:Adrenergic beta-2 Receptor Antagonists; D000319:Adrenergic beta-Antagonists / Q000737:chemistry; D000526:Alprenolol / Q000737:chemistry; D016880:Anisotropy; D004837:Epinephrine / Q000737:chemistry; D006801:Humans; D007545:Isoproterenol / Q000737:chemistry; D007700:Kinetics; D008024:Ligands; D008051:Lipid Bilayers / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry; D011412:Propanolamines / Q000737:chemistry; D011485:Protein Binding; D011510:Proteolipids / Q000737:chemistry; D018343:Receptors, Adrenergic, beta-2 / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods; D020349:Surface Plasmon Resonance / Q000379:methods*
D000322:Adrenergic Agonists; D058666:Adrenergic beta-2 Receptor Agonists; D058672:Adrenergic beta-2 Receptor Antagonists; D000319:Adrenergic beta-Antagonists; D008024:Ligands; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D011412:Propanolamines; D011510:Proteolipids; D018343:Receptors, Adrenergic, beta-2; C026777:ICI 118551; D000526:Alprenolol; D007545:Isoproterenol; D004837:Epinephrine