Patch-clamp studies of ion transport in isolated plant vacuoles

Plant cell vacuoles act as storage depots for substances such as sugars, organic and inorganic ions, many of which are commercially important. We have used the patch-clamp technique to characterize an ATP-dependent proton pump and a non-selective channel in the vacuolar membrane in single isolated barley leaf vacuoles. The large (60 to 80 pS) ion channel shows inward rectification, and carries both K + or malate ions driven by their concentration gradient as well as the electrical gradient established by the ATP-dependent proton pump.