The plasma membrane Ca(2+)-pumping ATPase (Ca(2+)-ATPase) is responsible for maintaining calcium homeostasis in eukaryotic cells. The Ca(2+)-ATPase is a family of pumps that are encoded by at least four genes. A cDNA for the human version of Ca(2+)-ATPase isoform PMCA2 was isolated and characterized. Comparison of the human and rat cDNA sequences showed that they were 95% homologous in the coding domain, and this homology was reflected in the deduced protein sequence where greater than 98% homology between the human and rat sequences was found. The amino acid differences that were found were almost all conservative. The PMCA2 cDNA was used to probe Southern blots of human-rodent somatic cell hybrid DNAs; the results indicated that the human PMCA2 gene was located on chromosome 3.