Fast-twitch and slow-twitch/cardiac Ca2+ ATPase genes map to human chromosomes 16 and 12

The fast-twitch and slow-twitch/cardiac Ca2+ ATPase genes have been assigned to human chromosomes 16 and 12, respectively, using rodent-human somatic cell hybrids and filter hybridization analysis of cell hybrid DNA. A rabbit cDNA for the fast-twitch ATPase hybridizes to a prominent single fragment in human genomic DNA digested with the restriction enzyme BamHI. By correlating the presence of this fragment in somatic cell hybrid DNA with the human chromosome content of the hybrids, the fast-twitch ATPase gene can be assigned to human chromosome 16. A slow-twitch/cardiac ATPase cDNA clone was isolated from a human muscle cDNA library and used to detect human fragments in EcoRI-digested somatic cell hybrid DNA. By correlating the presence of these fragments with the human chromosome content of the hybrids, the slow-twitch/cardiac ATPase gene can be assigned to human chromosome 12. Thus, the two ATPase genes, which are probably related to each other by an ancient duplication event, are not syntenic in the human genome.