Immunochemical demonstration of alpha 3 isozyme of Na,K-ATPase in human brain.

The catalytic alpha (alpha) subunit of the human Na,K-ATPase is encoded by multiple genes, as revealed from molecular cloning studies, yet the presence of the alpha 3 isoform has still not been resolved. We investigated the human alpha 3 isoform by Western blotting employing polyclonal anti-rat brain alpha 3 fusion protein, and purified human and rat axolemma Na,K-ATPase preparations. The antibody to rat brain alpha 3 fusion protein cross-reacted with both human and rat antigens, and the stained band superimposed on the alpha 2 band. This result suggests that alpha 3 isoform also exists in human brain.