Principal Investigators

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P10  Klaus Fendler
Professor

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P10  Ernst Bamberg
Professor and Director

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The proteins of interest are from the domains of ion channels and secondary active transporters. Using electrical, electrophysiological and spectroscopic methods the transport properties of these proteins are investigated in native systems (mammalian cell lines and oocytes) and in model membranes (proteoliposomes and planar lipid membranes). More specifically, the recently discovered light-gated ion channels Channelrhodopsin1 and 2 (ChR1,2) and secondary active transporters like the Na⁺/H⁺-exchanger NhaA are studied.

Light gated ion channels. Recently, the light gated cation channels Channelrhodopsins (ChR1,2) have been discovered. They represent with the seven transmembrane helix motif a novel class of ion channels. These microbial rhodopsins-like proteins are a long sought tool for the light stimulated remote control of neural cells in culture as well as in the brain of living animals with a superior spatial and time resolution. This optogenic approach has revolutionized the neurosciences methodologically in many respects and is used in numerous neurobiologically-oriented laboratories worldwide. However, only little is known about the mechanism of these ion channels. Therefore, the function and structure of these membrane proteins need to be investigated in detail and new Channelrhodopsins will be designed for optimal application in neuro- and cell biology.

Secondary active transporters. The mechanism of various transporters has been studied in our laboratory using current measurements on a solid supported membrane (SSM-based electrophysiology) in combination with spectroscopic techniques. Further progress towards a detailed understanding of the transport mechanism may be obtained using time resolved information allowing the identification of partial reactions and the determination of rate constants. We have, therefore, made an attempt to increase the time resolution of the SSM system in order to approach the time scale of protein conformational transitions. Indeed, we were able to obtain a time resolution as low as 2 ms.

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