H+, K(+)-ATPASE in the kidney: localization and function in the nephron.

In the past few years, many studies aimed at characterizing the localisation, the molecular nature, and the pharmacological and functional properties of renal H+, K(+)-ATPases. These studies included: (1) molecular cloning (by homology with other known P-type K(+)-ATPases) and expression of H+, K(+)-ATPase alpha-subunits from amphibian and mammalian epithelia; (2) kinetic and pharmacological characterization of K(+)-ATPase activities different from Na+, K(+)-ATPase in single segments of rat nephron, and (3) analysis of K+ and/or H+ transport in isolated collecting ducts from rat or rabbit kidney. The present paper summarizes these data with a special emphasis on those which demonstrate the existence along the mammalian nephron of several forms of H+, K(+)-ATPase displaying distinct biochemical, pharmacological and functional properties.