In vitro ~NA-arnp~l~cation techmque has been utdmed to generate a 430 bp fragment of the Na+,K+-ATPase, and a 550 bp fragment of a Ca2+-ATPase (the sarcoplasmtc reticulum-type) of Drosoph&~ melunogaster The ohgonucleotrde prtmers for the DNA-ampbficatton (Polymerase Cham Reaction) had been desrgned on the basis of ammo acid sequence motifs -the phosphorylatton site and the ATP-bmdmg sate -conserved among members of the ATPase protein famdy Usmg the amphfied cDNA-segments as probes, we demonstrated that there IS one Na+,K+-ATPase and one CaZ+-ATPase (sarcoplasmrc rettculum-type) gene m the Drosophda genome Three dtfferent mRNA species are processed from the Na+,K+-ATPase gene and one from the Ca s+-ATPase gene Developmental control m expression of the Ca2+-ATPase gene was observed Homology pnmer, Polymerase chain reaction, ATPase, Deveiopmental control of gene expresston, (Drasaph~~u me~~ag~ter)