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TOP3B
Releases the supercoiling and torsional tension of DNA introduced during the DNA replication and transcription by transiently cleaving and rejoining one strand of the DNA duplex. Introduces a single-strand break via transesterification at a target site in duplex DNA. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(5'-phosphotyrosyl)-enzyme intermediate and the expulsion of a 3'-OH DNA strand. The free DNA strand than undergoes passage around the unbroken strand thus removing DNA supercoils. Finally, in the religation step, the DNA 3'-OH attacks the covalent intermediate to expel the active-site tyrosine and restore the DNA phosphodiester backbone. Possesses negatively supercoiled DNA relaxing activity. Belongs to the type IA topoisomerase family. Isoform 1 is found in testis, heart and skeletal muscle. A 4 kb transcript which probably represents isoform 2 is found in thymus, kidney and pancreas. 3 alternatively spliced human isoforms have been reported. Note: This description may include information from UniProtKB.
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| Protein type: DNA-binding; EC 5.99.1.2; Topoisomerase |
| Chromosomal Location of human Ortholog: 22q11.22 |
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Cellular Component:
condensed chromosome; DNA topoisomerase III-beta-TDRD3 complex; nucleus
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Molecular Function:
DNA binding; DNA topoisomerase activity; DNA topoisomerase type I (single strand cut, ATP-independent) activity; protein binding
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Biological Process:
chromosome segregation; DNA topological change
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Reference #:
O95985
(UniProtKB)
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Alt. Names/Synonyms: DNA topoisomerase 3-beta-1; DNA topoisomerase III beta; DNA topoisomerase III beta-1; FLJ39376; TOP3B; TOP3B1; topoisomerase (DNA) III beta; topoisomerase III beta
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Gene Symbols: TOP3B
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Molecular weight:
96,662 Da
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Basal Isoelectric point:
8.47
Predict pI for various phosphorylation states
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