The insect plasma membrane H+ V-ATPase: intra-, inter-, and supramolecular aspects.

The plasma membrane H+ V-ATPase from the midgut of larval Manduca sexta, commonly called the tobacco hornworm, is the sole energizer of epithelial ion transport in this tissue, being responsible for the alkalinization of the gut lumen up to a pH of more than 11 and for any active ion movement across the epithelium. This minireview deals with those topics of our recent research on this enzyme that may contribute novel aspects to the biochemistry and physiology of V-ATPases. Our research approaches include intramolecular aspects such as subunit topology and the inhibition by macrolide antibiotics, intermolecular aspects such as the hormonal regulation of V-ATPase biosynthesis and the interaction of the V-ATPase with the actin cytoskeleton, and supramolecular aspects such as the interactions of V-ATPase, K+/H+ antiporter, and ion channels, which all function as an ensemble in the transepithelial movement of potassium ions.