The plasma membrane (PM) H+ -ATPase is an important ion pump in the plant cell membrane. By extruding protons from the cell and generating a membrane potential, this pump energizes the PM, which is a prerequisite for growth. Modification of the autoinhibitory terminal domains activates PM H+ -ATPase activity, and on this basis it has been hypothesized that these regulatory termini are targets for physiological factors that activate or inhibit proton pumping. In this review, we focus on the posttranslational regulation of the PM H+ -ATPase and place regulation of the pump in an evolutionary and physiological context. The emerging picture is that multiple signals regulating plant growth interfere with the posttranslational regulation of the PM H+ -ATPase.

INTRODUCTION

The plasma membrane (PM) H+ -ATPase is an electrogenic pump that exports cellular protons. In addition to generating a transmembrane chemical gradient of H+ (DpH; acidic on the outside), it also establishes an electrical gradient (the membrane potential; negative on the inside). As almost all other transport proteins in the plant PM are energized by this combined electrochemical gradient of protons, it has been a long-standing hypothesis in plant physiology that the PM H+ – ATPase is a powerhouse for plant growth (reviewed in Palmgren, 2001; Arango et al., 2003; Sondergaard et al., 2004; Duby and Boutry, 2009). However, although the biochemistry of the pump is known in great detail and its structure has been determined (reviewed in Morth et al., 2011), strong evidence for its role in plant growth has remained sparse until recently, when strong links between posttranslational regulation of PM H+ -ATPase and essential physiological functions of plants have emerged. The aim of this review is to provide an overview of this exciting and rapidly developing field.