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Updated: Jul 16, 2026

Green Fluorescent Protein-based Expression Screening of Membrane Proteins in Escherichia coli
Published on: January 6, 2015
Channelrhodopsin-1: a light-gated proton channel in green algae
Georg Nagel1, Doris Ollig, Markus Fuhrmann
1Max-Planck-Institut für Biophysik, Kennedyallee 70, 60596 Frankfurt am Main, Germany. nagel@mpibp-frankfurt.mpg.de
Abstract:
Phototaxis and photophobic responses of green algae are mediated by rhodopsins with microbial-type chromophores. We report a complementary DNA sequence in the green alga Chlamydomonas reinhardtii that encodes a microbial opsin-related protein, which we term Channelopsin-1. The hydrophobic core region of the protein shows homology to the light-activated proton pump bacteriorhodopsin. Expression of Channelopsin-1, or only the hydrophobic core, in Xenopus laevis oocytes in the presence of all-trans retinal produces a light-gated conductance that shows characteristics of a channel selectively permeable for protons. We suggest that Channelrhodopsins are involved in phototaxis of green algae.
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