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

We examined the effect of the β-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 β-subunit of the Na+/K+ or the H+/K+ ATPase. Immunoprecipitation with antiserum specific for the β-subunit of the Na+/K+ or the H+/K+ ATPase yielded not only the respective β-subunit but also the SR Ca2+ ATPase,indicating that the SR Ca2+ ATPase was associated with theβ-subunits of the Na+/K+ and the H+/K+ ATPases. Pulse-chase experiments revealed that the complex between the SR Ca2+ ATPase and the β-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 β-subunit of the Na+/K+ and H+/K+ ATPases.