ASSEMBLY OF NA,K-ATPASE ALPHA-SUBUNIT ISOFORMS WITH NA,K-ATPASE BETA-SUBUNIT ISOFORMS AND H,K-ATPASE BETA-SUBUNIT

cDNA encoding an epitope tag was joined to cDNAs encoding the chicken Na,K-ATPase beta 1 and beta 2 and H,K-ATPase beta-subunits to allow re cognition of these beta-subunits with the same monoclonal antibody dur ing assembly assays. cDNAs encoding chicken Na,K-ATPase alpha 1, alpha 2, or alpha 3 and Na,K-ATPase beta 1 or beta 2 or H,K-ATPase beta-sub units were transiently coexpressed in mammalian cells. Subunit assembl y was assayed by immune precipitation of alpha-isoforms with a monoclo nal antibody to the epitope-tagged beta-subunits. Each of the chicken alpha-isoforms assembled with each of the Na,K-ATPase beta-subunits an d the H,K-ATPase beta-subunit. Each of the epitope-tagged beta-subunit s also assembled with a Na,K-ATPase/Ca-ATPase chimera that retained on ly 26 amino acids of the Na,K-ATPase alpha-subunit, demonstrating that all three beta-subunits recognize this same alpha-subunit assembly si te.