Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:5.99.1.2 (topoisomerase)
 9,166 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A number of characteristics in the human genetic disorder ataxia-telangiectasia are compatible with an alteration to chromatin structure or the recognition of that structure by an enzyme or DNA binding protein. We describe here reduce activity of DNA topoisomerase type II in a number of Epstein Barr Virus-transformed ataxia-telangiectasia lymphoblastoid cell lines. Enzyme activity was reduced 10-fold or greater in 4 out of 5 cell lines compared to controls. In the remaining cell line approximately a 2-3 fold reduction was evident in partially purified extracts. DNA topoisomerase type I activity was found to be the same as controls in all the cell lines. Northern blot analysis revealed that the same level of DNA topoisomerase II mRNA was expressed in ataxia-telangiectasia and control cell lines. The size and amount of the enzyme did not differ appreciably from that observed in control cells. The reduced activity of DNA topoisomerase II in ataxia-telangiectasis cells might be explained by amino acid substitutions, small deletions in DNA or by a defect in post-translational modification in these cells.
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PMID:Defective DNA topoisomerase II in ataxia-telangiectasia cells. 196 59

We have provided evidence recently for a defect in DNA topoisomerase II in ataxia--telangiectasia (A-T) lymphoblastoid cells. This study was initiated to investigate in greater detail the nature of this defect. Southern hybridization analysis was carried out on DNA from control and A-T Epstein--Barr virus-transformed lymphoblastoid cells. The pattern of digestion, using several restriction enzymes, was the same in both cell types. Expression of topoisomerase II mRNA occurred to the same extent and there was no difference in the size of mRNA between the cell types. Western blot analysis revealed that the same amount of a major band of topoisomerase II protein was present in A-T and control cells but there was evidence for a reduced amount of a lower-molecular-weight form in A-T only. Extraction and purification did not lead to alteration in size of the enzyme or in amount recovered.
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PMID:Study of DNA topoisomerase II in ataxia-telangiectasia cells. 247 31