1F4Z:
reference: Coupling photoisomerization of retinal to directional transport in bacteriorhodopsin., Luecke H, Schobert B, Cartailler JP, Richter HT, Rosengarth A, Needleman R, Lanyi JK, J Mol Biol 2000 Jul 28;300(5):1237-55. PMID: 10903866

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