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 alpha- and beta-subunits derived from the cloned cDNAs into the oocytes. The oligosaccharide-deficient ATPase thus synthesized was transported to the oocyte 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 beta-subunit has no effect on the catalytic activities of (Na,K)ATPase.