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Cation channels by subunit III of the channel portion of the chloroplast H + ‐ATPase
Author(s) -
Schönknecht G.,
Althoff G.,
Apley E.,
Wagner R.,
Junge W.
Publication year - 1989
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 - 10.1016/0014-5793(89)81650-3
Subject(s) - chemistry , vesicle , potassium , biophysics , sodium , potassium channel , conductance , protein subunit , patch clamp , membrane , biochemistry , biology , mathematics , organic chemistry , combinatorics , gene , receptor
The chloroplast H + ‐ATPase (CF 0 CF 1 ) was isolated and reconstituted into lipid vesicles by dialysis technique. Vesicles were fused by dehydration/ rehydration to obtain cell‐size liposomes, which were studied by patch‐clamp techniques. Single‐channel activity was observed with several conductance levels in the range of some 10 pS (100 mM KCl). In contrast to intact CF 0 , which conducts protons, only (even at pH 8), these channels were permeable for potassium and sodium. Venturicidin, which blocks proton flow through intact CF 0 , here greatly decreased the single‐channel open probability. Subunit III of CF 0 , alone, yielded cation channels resembling the former. Our tentative interpretation is, that dearrangement or fragmentation of CF 0 caused the potassium and sodium permeability, which, however, is suppressed in intact CF 0 .