4HYJ:
reference: Structural insights into the proton pumping by unusual proteorhodopsin from nonmarine bacteria., Gushchin I, Chervakov P, Kuzmichev P, Popov AN, Round E, Borshchevskiy V, Ishchenko A, Petrovskaya L, Chupin V, Dolgikh DA, Arseniev AA, Kirpichnikov M, Gordeliy V, Proc Natl Acad Sci U S A. 2013 Jul 30;110(31):12631-6. doi:, 10.1073/pnas.1221629110. Epub 2013 Jul 19. PMID: 23872846

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