We describe here an easy system for the production of mg amounts of the rabbit Ca²⁺-ATPase SERCA 1a in the yeast S. cerevisiae. The protein is present in several membranes, including the plasma membrane of the yeast, in a native conformation. It can be purified by immunoprecipitation and can be phosphorylated from ATP in a Ca²⁺-dependent manner. Using a temperature-sensitive secretion mutant strain, the fully active protein can also be obtained in secretory vesicles.