Open AccessThylakoid membranes contain a high‐conductance channel
Author(s) -
Hinnah Silke C.,
Wagner Richard
Publication year - 1998
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1998.2530606.x
Subject(s) - thylakoid , membrane , conductance , biophysics , lucifer yellow , permeation , chemistry , analytical chemistry (journal) , chromatography , biology , biochemistry , chloroplast , physics , gap junction , intracellular , gene , condensed matter physics
Ion channels in the thylakoid membrane were investigated by direct patch clamping on swollen thylakoids. A preparation method has been developed in order to release osmotically swollen intact thylakoids from pea protoplasts derived from cotyledons of young Pisum sativum plants. The swollen thylakoids with typical diameters between 10 μm and 20 μm formed reproducibly high‐resistance seals with patch pipettes. We observed a potassium channel with a main conductant state of @KL ≈ 40 pS and a conductance of @KL ≈ 90 pS (in asymmetric 20/100 mM KCl) for the fully open channel. Surprisingly, the thylakoid membranes also contained a high‐conductance channel with a main conductant state of @KL ≈ 620 pS (in asymmetric 20/100 mM KCl), revealing also higher and lower conductant states. With a different experimental approach we showed that thylakoids are able to accumulate transiently the membrane impermeant fluorescent dye Lucifer Yellow which likewise suggests the presence of a pore‐like channel with a diameter large enough to allow permeation of Lucifer Yellow.