Methods of reconstitution of the purified sarcoplasmic reticulum (Ca(2+)-Mg2+)-ATPase using bile salt detergents to form membranes of defined lipid to protein ratios or sealed vesicles.

A detailed methodology is presented of two reconstitution protocols for the (Ca(2+)-Mg2+)-ATPase from rabbit skeletal muscle, using the detergent potassium cholate. Method A was shown to produce fully fragmented membranes of definable lipid to protein ratios, which were unable to take up calcium upon hydrolysis of ATP. This protocol was shown to produce a homologous population of membranes with respect to their lipid and protein composition at lipid to protein ratios up to 900:1 (mol/mol). Method B produced vesicles only of high lipid to protein ratios (3000:1), which have the ability to accumulate calcium on addition of ATP. Calcium accumulation and ATP hydrolysis for the ATPase reconstituted into different fatty acyl chain length phospholipids were also studied.