Functional activity of oligosaccharide-deficient (Na,K)ATPase expressed in Xenopus oocytes

(Na,K)ATPase from Torpedo californica was expressed in Xenopus laevis oocytes in the presence of tunicamycin by injecting mRNAs for the α- and β-subunits derived from the cloned cDNAs into the oocytes. The oligosaccharide-deficient ATPase thus synthesized was transported to the oocytes plasma membrane, where it exhibited virtually the same ATPase activity, ouabain-binding capacity and 86Rb + transport activity as the fully glycosylated enzyme. We conclude that the oligosaccharide chains on the β-subunit has no effect on the catalytic activities of (Na,K)ATPase.