In this study, we have followed the fate of newly synthesized α- and β-subunits of Na,K-ATPase in Xenopus oocytes injected with α and/or β cRNA to examine whether assembly of the two subunits is needed for a correct folding and/or for intracellular transport of Na,K-ATPase. Our data indicate that (1) assembly of α- and β-subunits occurs at the level of the ER, (2) β-subunits are needed for the newly synthesized α-subunit to adopt a stable configuration and (3) α- and β-subunits mutually depend on each other to be transported out of the ER.
