Fig. 2. Short-term labeling of the SR Ca²⁺ ATPase. The oocytes that had been directly injected with radiolabeled amino acids as described in Materials and Methods, were incubated in modified Barth's medium for 3-30 minutes. The microsomes from the labeled oocytes were immunoprecipitated with antisera specific for the SR Ca²⁺ ATPase (lanes 1-4) and for the ß-subunit of the Na⁺/K⁺ ATPase (lanes 5-8).