Cell Electrophysiology and Membrane Transport

Abstract

Cell electrophysiology endeavours to identify and characterize electrically active transport proteins in the plasmalemma and tonoplast. The preceding article within this series (Vol. 44, 1982) focussed on membrane ATPases (proton pump) and transport driven by the transmembrane proton electrochemical gradient, $\Delta \tilde \mu _H +$. This review is confined to two topics. The central role of the protonmotive force (pmf, ${{\Delta \tilde \mu _H + } \mathord{\left/ {\vphantom {{\Delta \tilde \mu _H + } F}} \right. \kern-\nulldelimiterspace} F}$) for so many transport processes requires accurate determination of its components, the transmembrane difference in electrical potential ψm, and H⁺ concentration, ΔpH. Current literature reveals that there has been significant progress in the technology of recording these parameters and, secondly, that the pitfalls and limitations of the avail-able techniques are often not adequately appreciated. The second topic is potassium transport, a genuinely electrophysiological matter. Two other fields of great interest in recent years are transport across the tonoplast, and co-transport of sugars and amino acids. Both topics have been thoroughly reviewed in 1984 by CLARKSON and LÜTTGE in Vol. 46 of this series, and by REINHOLD and KAPLAN.