[A possible role of the beta subunit of (Na, K)ATPase on the biogenesis of the enzyme].

(Na, K)ATPase is composed of two heterologus subunits; a catalytic alpha subunit and a glycosylated beta subunit whose role remains unclear. To elucidate a possible role of the beta subunit, the alpha and beta subunits of Torpedo californica (Na, K)ATPase were expressed in the Xenopus oocytes system which allows the specific programmed synthesis of different subunits in a cell by alternately injecting individual mRNA. When oocytes were injected with mRNA alpha alone, no significant increase in (Na, K)ATPase activity was observed, whereas a slight increase was detected in oocytes injected with mRNA beta alone. The pre-existing beta subunit, which had been synthesized by injecting mRNA beta, could assemble with the alpha subunit, expressed later in the single oocytes and the resulting alpha beta acquired both ouabain-binding and (Na, K)ATPase activities. The results reported in this paper strongly indicate that the beta subunit plays an essential role, at least in the biogenesis of the enzyme.