Selectivity of the fast activating vacuolar cation channel

Abstract

The FV channel dominates the ion conductance of the vacuolar membrane at physiological Ca2+ concentrations. Patch-clamp measurements on whole barley (Hordeum vulgare) mesophyll vacuoles and on excised tonoplast patches showed small differences in a selectivity sequence NH4/+>K+≥Rb+≥Cs+>Na+>Li+. Less permeant cations decreased the open probability. The FV channel allows the uptake of small monovalent cations especially NH4/+ into the vacuole.