R. Hanai et al., HUMAN TOP3 - A SINGLE-COPY GENE ENCODING DNA TOPOISOMERASE-III, Proceedings of the National Academy of Sciences of the United Statesof America, 93(8), 1996, pp. 3653-3657
A human cDNA encoding a protein homologous to the Escherichia coli DNA
topoisomerase I subfamily of enzymes has been identified through clon
ing and sequencing, Expressing the cloned human cDNA in yeast Delta to
p1 cells lacking endogenous DNA topoisomerase I yielded an activity in
cell extracts that specifically reduces the number of supercoils in a
highly negatively supercoiled DNA, On the basis of these results, the
human gene containing the cDNA sequence has been denoted TOP3, and th
e protein it encodes has been denoted DNA topoisomerase III. Screening
of a panel of human-rodent somatic hybrids and fluorescence in situ h
ybridization of cloned TOP3 genomic DNA to metaphase chromosomes indic
ate that human TOP3 is a single-copy gene located at chromosome 17p11.
2-12.