Topoisomerase I identified by scleroderma 70 antisera: enrichment of topoisomerase I at the centromere in mouse mitotic cells before anaphase.
Antibodies derived from scleroderma patients positive for the extractable 70-kDa antigen were shown to react with topoisomerase I. Topoisomerase I was identified by molecular size and by antibody inhibition of the topoisomerase I-specific relaxation of supercoiled plasmid DNA. By using in situ localization by indirect fluorescence, we found topoisomerase I preferentially located in the centromeric regions of the mouse G2-phase cells and chromosomes, while the distribution in human cells is much more dispersed. Moreover, comparison of a published consensus sequence for topoisomerase I binding with mouse satellite DNA revealed a high degree of homology. The localization of topoisomerase I in the centromeres of mouse cells in the later part of the cell cycle and prior to anaphase suggests functional involvement in mitosis.
D000818:Animals; D000918:Antibody Specificity; D001323:Autoantibodies / Q000276:immunology; D002460:Cell Line; D002503:Centromere / Q000032:analysis*; D002875:Chromosomes / Q000032:analysis*; D004264:DNA Topoisomerases, Type I / Q000032:analysis* / Q000276:immunology; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D007399:Interphase; D007526:Isoelectric Point; D051379:Mice; D008938:Mitosis; D008970:Molecular Weight; D009687:Nuclear Proteins; D009698:Nucleoproteins / Q000276:immunology / Q000302:isolation & purification; D012595:Scleroderma, Systemic / Q000276:immunology; D012689:Sequence Homology, Nucleic Acid
D001323:Autoantibodies; D009687:Nuclear Proteins; D009698:Nucleoproteins; C048100:Scl 70 antigen, human; D004264:DNA Topoisomerases, Type I