title: Human topoisomerase I is phosphorylated in vitro on its amino terminal domain by protein kinase NII.
abstract: Topoisomerase I purified from HeLa cells was phosphorylated in vitro with protein kinase NII (pkNII) purified from calf thymus: this phosphorylation was inhibited by heparin. A peptide containing a sequence corresponding to a putative pkNII phosphorylation site in topoisomerase I was synthesized and phosphorylated with pkNII. HPLC and two-dimensional analysis show identity between the synthetic phosphorylated peptide and one topoisomerase I phosphopeptide indicating Ser10 as one of the in vitro pkNII phosphorylation sites in topoisomerase I.
authors.affiliation: Dipartimento di Biologia Cellulare e Molecolare, Universita' di Perugia, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Cardellini
authors.forename: M
authors.initials: M
authors.lastname: Bramucci
authors.forename: G L
authors.initials: GL
authors.lastname: Gianfranceschi
authors.forename: E
authors.initials: E
authors.lastname: Durban
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*
chemical_list: D011494:Protein Kinases; C026813:protein kinase NII; D004264:DNA Topoisomerases, Type I