3UG9:
reference: Crystal structure of the channelrhodopsin light-gated cation channel., Kato HE, Zhang F, Yizhar O, Ramakrishnan C, Nishizawa T, Hirata K, Ito J, Aita Y, Tsukazaki T, Hayashi S, Hegemann P, Maturana AD, Ishitani R, Deisseroth K, Nureki O, Nature. 2012 Jan 22;482(7385):369-74. doi: 10.1038/nature10870. PMID: 22266941

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