Cellular and Molecular Life Sciences

, Volume 64, Issue 18, pp 2323–2328

Xanthorhodopsin: Proton pump with a carotenoid antenna


    • Department of Physiology and BiophysicsUniversity of California
  • J. K. Lanyi
    • Department of Physiology and BiophysicsUniversity of California
Visions & Reflections (Minireview)

DOI: 10.1007/s00018-007-7167-y

Cite this article as:
Balashov, S.P. & Lanyi, J.K. Cell. Mol. Life Sci. (2007) 64: 2323. doi:10.1007/s00018-007-7167-y


Retinal proteins function as photoreceptors and ion pumps. Xanthorhodopsin of Salinibacter ruber is a recent addition to this diverse family. Its novel and distinctive feature is a second chromophore, a carotenoid, which serves as light-harvesting antenna. Here we discuss the properties of this carotenoid/retinal complex most relevant to its function (such as the specific binding site controlled by the retinal) and its relationship to other retinal proteins (bacteriorhodopsin, archaerhodopsin, proteorhodopsin and retinal photoreceptors of archaea and eukaryotes). Antenna addition to a retinal protein has not been observed among the archaea and emerged in bacteria apparently in response to environmental conditions where light-harvesting becomes a limiting factor in retinal protein functioning.


Light energy transfersalinixanthinproton transportcarotenoid binding

Copyright information

© Birkhäuser Verlag, Basel 2007