Antisera Specific for the α1, α2, α3, and β Subunits of the Na,K-ATPase: Differential Expression of α and β Subunits in Rat Tissue Membranes

We have developed a panel of antibodies specific for the α1, α2, α3, and β subunits of the rat Na,K-ATPase. TrpE-α subunit isoform fusion proteins were used to generate three antisera, each of which reacted specifically with a distinct a subunit isotype. Western blot analysis of rat tissue microsomes revealed that α1 subunits were expressed in all tissues while al subunits were expressed in brain, heart, and lung. The α3 subunit, a protein whose existence had been inferred from cDNA cloning, was expressed primarily in brain and copurified with ouabain-inhibitable Na,K-ATPase activity. An antiserum specific for the rat Na,K-ATPase β subunit was generated from a TrpE-β subunit fusion protein. Western blot analysis showed that β subunits were present in kidney, brain, and heart. However, no β subunits were detected in liver, lung, spleen, thymus, or lactating mammary gland. The distinct tissue distributions of α and β subunits suggest that different members of the Na,K-ATPase family may have specialized functions.