Vacuolar cation/proton exchanger (CAX). Translocates Ca(2+) and other metal ions into vacuoles using the proton gradient formed by H(+)-ATPase and H(+)-pyrophosphatase (By similarity). Involved in ion homeostasis in association with CAX1. Inhibited by excess of Ca(2+). Tonoplast. Expressed in roots, stems and flowers. By Ca(2+), Mg(2+) and Na(+). Belongs to the Ca(2+):cation antiporter (CaCA) (TC 2.A.19) family. Cation/proton exchanger (CAX) subfamily.