K(+)/H(+) antiporter involved in K(+) homeostasis and osmotic adjustment. Expressed in shoots and roots. Up-regulated by low K(+) stress and down-regulated by high K(+). No visible phenotype. Kea1 and kea2 double mutants display strong growth retardation along with pale green leaves. Kea1, kea2 and kea3 triple mutants are extremely stunted in size with entirely pale leaves and died before steeing seeds. The full-length protein being inactive in a heterologous system, the N-terminal region seems to have a regulatory or auto-inhibitory function. Belongs to the monovalent cation:proton antiporter 2 (CPA2) transporter (TC 2.A.37) family. KEA (TC 2.A.37.1) subfamily. Truncated N-terminus. Was originally thought to correspond to two different genes. Was originally thought to correspond to two different genes.