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Photosynthetic reaction center (RC) complex, subunit H; RC is an integral membrane protein-pigment complex which catalyzes light-induced reduction of ubiquinone to ubiquinol, generating a transmembrane electrochemical gradient of protons used to produce ATP by ATP synthase. Subunit H is positioned mainly in the cytoplasm with one transmembrane alpha helix. Provides proton transfer pathway (water channels) connecting the terminal quinone electron acceptor of RC, to the aqueous phase. Found in photosynthetic bacteria: alpha, beta, and gamma proteobacteria.
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