Structural map of expression plasmids pPAP1666, pPAP4126, and pPAP4144. Plasmid pPAP1666 allows galactose-inducible transcription of α1 and β1 cDNAs encoding pig kidney Na,K-ATPase subunits. Plasmid pPAP2231 is identical to pPAP1666 except that the α1(TM4/TM5) DNA (encoding amino acids 348 to 748 from the pig Na,K-ATPase α1 subunit) has replaced the α1 cDNA, and the β1 cDNA has been removed. In pPAP3437 and pPAP2902, the α1(TM4/TM5) DNA has been replaced by the PMA1 coding region and rat PACR1 receptor cDNA, respectively. Expression from plasmids pPAP4126 and pPAP4144 is induced by doxycycline. Ampr, β-lactamase gene; p15A, p15A origin of replication; pUC19, origin of replication from pUC19; 2μ, 2μm origin of replication; ARS1-CEN4, autonomous replicating sequence and centromere region from yeast; URA3, yeast orotinin-5′-P decarboxylase gene; leu2-d, a poorly expressed allele of the yeast β-isopropylmalate dehydrogenase gene; TRP1, phosphoribosylanthranilate isomerase gene; CYC-GALP, a galactose-inducible promoter; CYC1-TATA, a crippled promoter from the cytochrome c gene; CMV, cytomegalovirus promoter; |, operator site from tetracycline resistance gene; tTA, reverse transactivator; α1 (pig) and β1 (pig), cDNAs encoding the α1 and β1 Na,K-ATPase subunits from the pig kidney.