Two different types of proton transporting ATPases, v-and p-type H(+)-ATPases engage in epithelial ion transport. Properties, function, molecular structure and distribution of these H(+)-ATPase (v-type) and H+, K(+)-ATPase (p-type) are summarized here. Intraorganellar spaces, such as lysosome, synapse, multivesicular body, are acidified by the vacuole-type H(+)-ATPases. Secretion of proton by some types of intercalated cells of kidney collecting tubules is due to H(+)-ATPase. Gastric proton secretion is due to H+, K(+)-ATPase. Proton secretion and absorption of potassium by distal colon is due to p-type ATPase.