Organelles of the secretory and endocytic pathways are distinguished by their luminal acidity, which is generated by the activity of an electrogenic vacuolar-type hydrogen ATPase. Progressive acidification of vesicles in the endocytic pathway is essential for the redistribution and degradation of internalized membrane proteins, such as ligand receptor complexes and fluid-phase solutes. This gene is expressed predominantly in the trans-Golgi network, and mediates the influx of sodium or potassium in exchange for hydrogen. It may thus play an important role in maintaining cation homeostasis and function of the trans-Golgi network. This gene is part of a gene cluster on chromosome Xp11.23. [provided by RefSeq, Jul 2008].
Function: Mediates electroneutral exchange of protons for Na(+) and K(+) across endomembranes. May contribute to Golgi volume and cation homeostasis.