Colorimetric Assays of Na,K-ATPase
1Laboratory of Membrane Biology, Massachusetts General Hospital, Edwards 4, 55 Fruit Street, Boston, MA, 02114, USA. sweadner@helix.mgh.harvard.edu.
Abstract:
The Na,K-ATPase is a plasma membrane enzyme that catalyzes active ion transport by the hydrolysis of ATP. Its activity in vivo is determined by many factors, particularly the concentration of intracellular sodium ions. It is the target of the cardiac glycoside class of drugs and of endogenous regulators. Its assay is often an endpoint in the investigation of physiological processes, and it is a promising drug target. As described in this unit, its enzymatic activity can be determined in extracts from tissues by test tube assay using a spectrophotometer or (32)P-ATP. The protocols in this chapter measure inorganic phosphate as the end product of hydrolysis of ATP.
