Purification and characterization of a type II DNA topoisomerase from bovine calf thymus.

Halligan, Brian D.; Edwards, K. A.; Liu, Leroy F.

doi:10.1016/s0021-9258(18)89578-3

Cited by 200 publications

(39 citation statements)

References 40 publications

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“…First, the antitopoisomerase II antiserum (which was raised against the scaffold-associated form of the enzyme) might detect only a subfraction of the total topoisomerase II. We believe this to be unlikely, since an independent antiserum raised against purified topoisomerase II from bovine calf thymus (20) gave identical results in immunoblotting experiments (data not shown). Differences in cross-species immu-noreactivity between these two antisera argue strongly that they recognize different epitopes on the protein.…”

Section: Detection Of Topoisomerase H In Erythroid Cells By Immunoblottingmentioning

confidence: 88%

Topoisomerase II: A specific marker for cell proliferation.

Heck¹,

Earnshaw²

1986

The Journal of Cell Biology

407

225

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Abstract.We have used an antibody probe to measure the levels of topoisomerase II in several transformed and developmentally regulated normal cell types. Transformed cells contain roughly 1 × 106 copies of the enzyme. During erythropoiesis in chicken embryos the enzyme level drops from 7.8 × 104 copies per erythroblast to <300 copies per erythrocyte concomitant with the cessation of mitosis in the blood. Cultured myoblasts also lose topoisomerase II upon fusion into nonproliferating myotubes. When peripheral blood lymphocytes (which lack detectable topoisomerase II) commence proliferation, they express topoisomerase II de novo. Appearance of the enzyme exactly parallels the onset of DNA replication. These results suggest that topoisomerase II is not required for transcription in higher eukaryotes, but that it may function during DNA replication. Furthermore, topoisomerase II is a sensitive and specific marker for proliferating cells.

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Section: Detection Of Topoisomerase H In Erythroid Cells By Immunoblottingmentioning

confidence: 88%

Topoisomerase II: A specific marker for cell proliferation.

Heck¹,

Earnshaw²

1986

The Journal of Cell Biology

407

225

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“…Two parallel procedures are described that are appropriate with either suspension cultures or cells growing as monolayers. Other methods have been described for isolation of extracts from tissues (Halligan et al, 1985), with the approach depending very much on the tissue being studied and the amount of available material.…”

Section: Support Protocolmentioning

confidence: 99%

Topoisomerase Assays

et al. 2012

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Topoisomerases are nuclear enzymes that play essential roles in DNA replication, transcription, chromosome segregation, and recombination. All cells have two major forms of topoisomerases: type I, which makes single-stranded cuts in DNA, and type II enzymes, which cut and pass double-stranded DNA. DNA topoisomerases are important targets of approved and experimental anti-cancer agents. The protocols described in this unit are of assays used to assess new chemical entities for their ability to inhibit both forms of DNA topoisomerase. Included are an in vitro assay for topoisomerase I activity based on relaxation of supercoiled DNA and an assay for topoisomerase II based on the decatenation of double-stranded DNA. The preparation of mammalian cell extracts for assaying topoisomerase activity is described, along with a protocol for an ICE assay for examining topoisomerase covalent complexes in vivo and an assay for measuring DNA cleavage in vitro.

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“…We have addressed the second explanation above by treating chromosomes in solution with rabbit anti-topoisomerase 1I (20,28). This antibody shows a wide interspecies crossreactivity not exhibited by the anti-cSc-1 antibody discussed above.…”

Section: W C Earnshaw and L F Liu Unpublished Observations)mentioning

confidence: 99%

Localization of topoisomerase II in mitotic chromosomes.

Earnshaw¹,

Heck²

1985

The Journal of Cell Biology

476

161

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In the preceding article we described a polyclonal antibody that recognizes cSc-1, a major polypeptide component of the chicken mitotic chromosome scaffold. This polypeptide was shown to be chicken topoisomerase II. In the experiments described in the present article we use indirect immunofluorescence and immunoelectron microscopy to examine the distribution of topoisomerase I1 within intact chromosomes. We also describe a simple experimental protocol that differentiates antigens that are interspersed along the chromatin fiber from those that occupy restricted domains within the chromosome. These experiments indicate that the distribution of the enzyme appears to be independent of the bulk chromatin. Our data suggest that topoisomerase II is bound to the bases of the radial loop domains of mitotic chromosomes.

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Purification and characterization of a type II DNA topoisomerase from bovine calf thymus.

Cited by 200 publications

References 40 publications

Topoisomerase II: A specific marker for cell proliferation.

Topoisomerase II: A specific marker for cell proliferation.

Topoisomerase Assays

Localization of topoisomerase II in mitotic chromosomes.

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