Microsomal Ouabain-Binding Factor in Electroplax Extracts 1

Summary

Lubrol WX extracts microsomal-bound ouabain-[³H] into the 50,000g supernatant fraction. The bound ouabain can be separated by chromatography with Sepharose and recovered in parallel fractions with recoverable adenosinetriphosphatase activity. Ouabain also binds to supernatant components in the Lubrol extracts and this bound ouabain has the same elution pattern as that bound to native microsomes prior to extraction with Lubrol. The proportion of bound ouabain that is recovered after chromatography is much greater than that of enzyme activity. Under these conditions, bound ouabain is a useful marker for enzyme extraction despite inactivation of the enzyme.