Right-side-out pumping Na,K-ATPase-liposomes: a new tool to study the enzyme's receptor function

The technology to prepare right-side-out pumping Na,K-ATPase-liposomes is described. The 50% right-side-out oriented pumps of ATP-containing liposomes are then activated by the addition of external Rb ions, leading to a ouabain-sensitive Rb-influx which is the mirror-image of the inside-out transport. The resulting internal Rb concentration is 4 to 10 fold larger than the external concentration. Finally, the accumulated Rb ions can be extruded by driving the 50% inside-out oriented pumps by external ATP.