Assembly of Na,K-ATPase α-subunit isoforms with Na,K-ATPase β-subunit isoforms and H,K-ATPase β-subunit

cDNA encoding an epitope tag was joined to cDNAs encoding the chicken Na,K-ATPase β1 and β2 and H,K-ATPase β-subunits to allow recognition of these β-subunits with the same monoclonal antibody during assembly assays. cDNAs encoding chicken Na,K-ATPase α1, α2, or α3 and Na,K-ATPase β1 or β2 or H,K-ATPase β-subunits were transiently coexpressed in mammalian cells. Subunit assembly was assayed by immune precipitation of α-isoforms with a monoclonal antibody to the epitope-tagged β-subunits. Each of the chicken α-isoforms assembled with each of the Na,K-ATPase β-subunits and the H,K-ATPase β-subunit. Each of the epitope-tagged β-subunits also assembled with a Na,K-ATPase/Ca-ATPase chimera that retained only 26 amino acids of the Na,K-ATPase α-subunit, demonstrating that all three β-subunits recognize this same α-subunit assembly site.