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Coupling of proton source and sink via H + ‐migration along the membrane surface as revealed by double patch‐clamp experiments
Author(s) -
Antonenko Yuri N,
Pohl Peter
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00590-0
Subject(s) - membrane , gramicidin , chemistry , conductance , proton , ion , analytical chemistry (journal) , ion channel , coupling (piping) , molecular physics , atomic physics , chemical physics , materials science , physics , chromatography , condensed matter physics , biochemistry , receptor , organic chemistry , quantum mechanics , metallurgy
Long‐range proton transfer along the surface of black lipid bilayers was observed between two integral membrane channels (gramicidins), one operating as a proton source, the other as a sink, by patch‐clamp technique. In contrast, potassium ions were shown to equilibrate with the aqueous bulk phase before being consumed. Both channels opened and closed simultaneously only if the charge between them was carried by protons. In this case an anomalous high conductance between two patched membrane fragments was measured, each of them containing one single gramicidin channel. The coupled state disappeared when the distance between these two channels was increased above the critical value. The latter was shown to increase with the channel lifetime. Our results support the idea of the `localized' proton coupling, in which protons that have been pumped across membranes migrate along the membrane surface to reach another membrane protein that utilizes the established pH gradient.