Eukaryotic DNA topoisomerase II, a ubiquitous ATP-dependent type II topoisomerase, is an essential nuclear enzyme in DNA replication and transcription, chromatin segregation, and cell cycle progression. These enzymes transiently break a pair of complementary strands in double-stranded DNA to form a gate for the passage of duplex DNA. Two isoforms of DNA topoisomerase II have been identified, topo IIα and topo IIß. These have a high degree of homology, except for some divergence in the C-terminal region. Both contain multiple bipartite nuclear localization sequences (NLS) that mediate their subnuclear localization. Topo IIα levels rise during late S phase and peak in G2-M, whereas topo IIß levels remain constant throughout the cell cycle. In addition, topo IIα is expressed in proliferating cells, while topo IIß is expressed in many tissues. The exact role of these two isoforms during cell proliferation is not known, however the differences in cellular expression implicate different physiological roles. Both isoforms may also be important targets for anticancer agents that exert cytotoxicity in proliferating cells via stabilization of a topo II-DNA complex.
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注意事项:
1.Since applications vary, each investigator should titrate the reagent to obtain optimal results.
2.Caution: Sodium azide yields highly toxic hydrazoic acid under acidic conditions. Dilute azide compounds in running water before discarding to avoid accumulation of potentially explosive deposits in plumbing.