KCO1 is a component of the slow-vacuolar (SV) ion channel

The Arabidopsis double pore K+ channel KCO1 was fused to green fluorescent protein and expressed in tobacco protoplasts. Microscopic analysis revealed a bright green fluorescence at the vacuolar membrane. RT-PCR experiments showed that KCO1 is expressed in the mesophyll. Vacuoles; from Arabidopsis wild-type and kco1 knockout plants were isolated for patch-clamp analyses. Currents mediated by slow-activating vacuolar (SV) channels of mesophyll cell vacuoles were significantly smaller in kco1 plants compared to the wild-type. This shown that KCO1 is involved in the formation of SV channels. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.