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J Biol Chem. 2015 Aug 14;290(33):20117-27. doi: 10.1074/jbc.M115.652172. Epub 2015 Jun 23.

The Activation Pathway of Human Rhodopsin in Comparison to Bovine Rhodopsin.

Author information

1
From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, 10115 Berlin, Germany, and.
2
From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, AG ProteInformatics, Charitéplatz 1, 10117 Berlin, Germany.
3
From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, AG Protein X-ray Crystallography and Signal Transduction, and.
4
From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin.
5
Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, 10115 Berlin, Germany, and eglof.ritter@hu-berlin.de.
6
From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Zentrum für Biophysik und Bioinformatik (BPI), Humboldt-Universität zu Berlin, 10115 Berlin, Germany.
7
From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, AG Protein X-ray Crystallography and Signal Transduction, and patrick.scheerer@charite.de.
8
From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, franz.bartl@charite.de.

Abstract

Rhodopsin, the photoreceptor of rod cells, absorbs light to mediate the first step of vision by activating the G protein transducin (Gt). Several human diseases, such as retinitis pigmentosa or congenital night blindness, are linked to rhodopsin malfunctions. Most of the corresponding in vivo studies and structure-function analyses (e.g. based on protein x-ray crystallography or spectroscopy) have been carried out on murine or bovine rhodopsin. Because these rhodopsins differ at several amino acid positions from human rhodopsin, we conducted a comprehensive spectroscopic characterization of human rhodopsin in combination with molecular dynamics simulations. We show by FTIR and UV-visible difference spectroscopy that the light-induced transformations of the early photointermediates are very similar. Significant differences between the pigments appear with formation of the still inactive Meta I state and the transition to active Meta II. However, the conformation of Meta II and its activity toward the G protein are essentially the same, presumably reflecting the evolutionary pressure under which the active state has developed. Altogether, our results show that although the basic activation pathways of human and bovine rhodopsin are similar, structural deviations exist in the inactive conformation and during receptor activation, even between closely related rhodopsins. These differences between the well studied bovine or murine rhodopsins and human rhodopsin have to be taken into account when the influence of point mutations on the activation pathway of human rhodopsin are investigated using the bovine or murine rhodopsin template sequences.

KEYWORDS:

G protein-coupled receptor (GPCR); human; protein dynamic; receptor; rhodopsin; structure-function

PMID:
26105054
PMCID:
PMC4536423
DOI:
10.1074/jbc.M115.652172
[Indexed for MEDLINE]
Free PMC Article

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