Intracellular NHX-Type Cation/H+ Antiporters in Plants

Cells depend on the homeostatic maintenance of pH within specific cellular compartments to ensure optimal conditions for metabolic and enzymatic processes as well as protein structure and function. In the animal secretory pathway, cells maintain distinct luminal pHs within various compartments (Paroutis et al., 2004). Among the many molecular players that contribute to pH and ion homeostasis in plants, Na+(K+)/H+ exchangers (also known as NHX-type cation/H+ antiporters) appear to be particularly important for the regulation of a wide variety of physiological processes, including cell expansion, cell volume regulation, osmotic adjustment, pH regulation, membrane trafficking, protein processing, and cellular stress responses (Pardo et al., 2006; Rodriguez-Rosales et al., 2009; Bassil et al., 2012).