| bacteriorhodopsin | <microbiology> A light driven proton pumping protein (248 residues, 26 kD), similar to rhodopsin, found in purple patches in the cytoplasmic membrane of the bacterium Halobacterium halobium. It is composed of 7 transmembrane helices and contains the light absorbing chromophore, retinal. Light absorption maxima: 568 nm (light adapted), 558 nm (dark adapted). Each photon results in the movement of 2 protons from cytoplasmic to extracellular sides of the membrane. The resulting proton gradient is used (amongst other things) to drive chemiosmotic synthesis of ATP. (18 Nov 1997) |
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