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Rokitskaya TI, Maliar N, Kovalev KV, Volkov O, Gordeliy VI, Antonenko YN. Rhodopsin Channel Activity Can Be Evaluated by Measuring the Photocurrent Voltage Dependence in Planar Bilayer Lipid Membranes. BIOCHEMISTRY (MOSCOW) 2021; 86:409-419. [PMID: 33941063 DOI: 10.1134/s0006297921040039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The studies of the functional properties of retinal-containing proteins often include experiments in model membrane systems, e.g., measurements of electric current through planar bilayer lipid membranes (BLMs) with proteoliposomes adsorbed on one of the membrane surfaces. However, the possibilities of this method have not been fully explored yet. We demonstrated that the voltage dependence of stationary photocurrents for two light-sensitive proteins, bacteriorhodopsin (bR) and channelrhodopsin 2 (ChR2), in the presence of protonophore had very different characteristics. In the case of the bR (proton pump), the photocurrent through the BLM did not change direction when the polarity of the applied voltage was switched. In the case of the photosensitive channel protein ChR2, the photocurrent increased with the increase in voltage and the current polarity changed with the change in the voltage polarity. The protonophore 4,5,6,7-tetrachloro-2-trifluoromethyl benzimidazole (TTFB) was more efficient in the maximizing stationary photocurrents. In the presence of carbonyl cyanide-m-chlorophenylhydrazone (CCCP), the amplitude of the measured photocurrents for bR significantly decreased, while in the case of ChR2, the photocurrents virtually disappeared. The difference between the effects of TTFB and CCCP was apparently due to the fact that, in contrast to TTFB, CCCP transfers protons across the liposome membranes with a higher rate than through the decane-containing BLM used as a surface for the proteoliposome adsorption.
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Affiliation(s)
- Tatyana I Rokitskaya
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
| | - Nina Maliar
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Kirill V Kovalev
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia.,Institut de Biologie Structurale (IBS), Université Grenoble Alpes, CEA, CNRS, Grenoble, 38044, France
| | - Oleksandr Volkov
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich GmbH, Juelich, 52425, Germany.,JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich GmbH, Juelich, 52425, Germany
| | - Valentin I Gordeliy
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia.,Institut de Biologie Structurale (IBS), Université Grenoble Alpes, CEA, CNRS, Grenoble, 38044, France.,Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich GmbH, Juelich, 52425, Germany.,JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich GmbH, Juelich, 52425, Germany
| | - Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
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VODYANOY V, VODYANOY I. The Role of ATP and GTP in the Mediation of the Modulatory Effects of Odorant on Olfactory Receptor Sites Functionally Reconstituted into Planar Lipid Bilayers. Ann N Y Acad Sci 1987. [DOI: 10.1111/j.1749-6632.1987.tb43665.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
The steady-state conductance of planar bimolecular lipid membranes (BLMs) modified with rat olfactory epithelial homogenate (ROH) becomes sensitive to very low concentrations of odorant in the presence of adenosine triphosphate (ATP) and guanosine triphosphate (GTP). The chemosensitivity is not observed when ATP and GTP are absent. Adenosine 3',5'monophosphate (cAMP) mimics the effect of the odorant. Effects of odorants and cAMP are dose dependent. These data are consistent with the hypothesis that cAMP is a second messenger in the initial steps of olfactory transduction.
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