Electroneutral K(+)/H(+) antiporter. Accelerates photosynthetic acclimation in fluctuating light environments. Enriched in the stromal lamellae. Expressed in shoots and roots. Up-regulated by low K(+) stress. No visible phenotype (PubMed:25451040, PubMed:24794527). Kea1, kea2 and kea3 triple mutants are extremely stunted in size with entirely pale leaves and died before steeing seeds (PubMed:24794527). Belongs to the monovalent cation:proton antiporter 2 (CPA2) transporter (TC 2.A.37) family. KEA (TC 2.A.37.1) subfamily.