Transient association of the sarcoplasmic reticulum Ca²⁺ ATPase with the Na⁺/K⁺-ATPase and H⁺/K⁺-ATPase -subunits during its biogenesis in Xenopus oocytes

We examined the effect of the -subunits of the Na⁺/K⁺ and H⁺/K⁺ ATPases on the biogenesis of the sarcoplasmic reticulum (SR) Ca²⁺ ATPase in Xenopus oocytes. Oocytes were simultaneously injected with cRNAs for both the SR Ca²⁺ ATPase and the -subunit of the Na⁺/K⁺ or the H⁺/K⁺ ATPase. Immunoprecipitation with antiserum specific for the -subunit of the Na⁺/K⁺ or the H⁺/K⁺ ATPase yielded not only the respective -subunit but also the SR Ca²⁺ ATPase, indicating that the SR Ca²⁺ ATPase was associated with the -subunits of the Na⁺/K⁺ and the H⁺/K⁺ ATPases. Pulse-chase experiments revealed that the complex between the SR Ca²⁺ ATPase and the -subunit of the Na⁺/K⁺ ATPase was formed transiently and dissociated during the course of maturation. This is the first report that demonstrates the association of the SR Ca²⁺ ATPase with the -subunit of the Na⁺/K⁺ and H⁺/K⁺ ATPases.