Abstract
Structural changes are central to the mechanism of light-driven proton transport by bacteriorhodopsin, a seven-helix membrane protein. The main intermediate formed upon light absorption is M, which occurs between the proton release and uptake steps of the photocycle. To investigate the structure of the M intermediate, we have carried out electron diffraction studies with two-dimensional crystals of wild-type bacteriorhodopsin and the Asp96 → Gly mutant. The M intermediate was trapped by rapidly freezing the crystals in liquid ethane following illumination with a xenon flash lamp at 5 and 25°C. Here, we present 3.5 Å resolution Fourier projection maps of the differences between the M intermediate and the ground state of bacteriorhodopsin. The most prominent structural changes are observed in the vicinity of helices F and G and are localized to the cytoplasmic half of the membrane.
Original language | English (US) |
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Pages (from-to) | 1-8 |
Number of pages | 8 |
Journal | The EMBO journal |
Volume | 12 |
Issue number | 1 |
State | Published - 1993 |
Keywords
- Conformational change
- M-intermediate
- Retinal proteins
- Seven-helix receptors
- Signal transduction
ASJC Scopus subject areas
- Cell Biology
- Genetics