Electron diffraction analysis of structural changes in the photocycle of bacteriorhodopsin

Sriram Subramaniam, Mark Gerstein, Dieter Oesterhelt, Richard Henderson

Research output: Contribution to journalArticlepeer-review

348 Scopus citations


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 languageEnglish (US)
Pages (from-to)1-8
Number of pages8
JournalThe EMBO journal
Issue number1
StatePublished - 1993


  • Conformational change
  • M-intermediate
  • Retinal proteins
  • Seven-helix receptors
  • Signal transduction

ASJC Scopus subject areas

  • Cell Biology
  • Genetics


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