Chemical and functional studies on the importance of purple membrane lipids in bacteriorhodopsin photocycle behavior.
In native purple membrane (PM), there are approximately 1 squalene, 2 glycolipid sulfate (GLS), and 6 phospholipid (PL) molecules per bacteriorhodopsin (BR) monomer. Brief (approximately 2 min) exposure to 0.1% Triton X-100 removes about 25%, 20%, and 6% of squalenes, GLS, and PL, respectively (this paper) while causing profound changes in the BR photocycle, including the loss of 'photocooperativity'. The BR photocycle in Triton-treated PM can be restored to near normal behavior by reconstitution with native PM lipids. Isolated squalenes are not effective whereas PL alone partially restores normal photocycle characteristics.
Dracheva
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Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Bose
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Hendler
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RW
D001436:Bacteriorhodopsins / Q000737:chemistry / Q000187:drug effects / Q000528:radiation effects*; D003902:Detergents / Q000494:pharmacology; D006017:Glycolipids / Q000032:analysis; D019617:Halobacterium salinarum; D008563:Membrane Lipids / Q000032:analysis*; D017830:Octoxynol / Q000494:pharmacology; D010743:Phospholipids / Q000032:analysis; D010777:Photochemistry; D018717:Purple Membrane / Q000737:chemistry*; D013185:Squalene / Q000032:analysis
D003902:Detergents; D006017:Glycolipids; D008563:Membrane Lipids; D010743:Phospholipids; D001436:Bacteriorhodopsins; D013185:Squalene; D017830:Octoxynol