Names & Taxonomy

Uniprot ID:
O95985
Entry Name:
TOP3B_HUMAN
Status:
reviewed
Protein Names:
DNA topoisomerase 3-beta-1 (EC 5.99.1.2) (DNA topoisomerase III beta-1)
Gene Names:
TOP3B TOP3B1
Gene Names Primary:
TOP3B
Organism:
Homo sapiens (Human)

Structure

Length:
862
Sequence:
MKTVLMVAEKPSLAQSIAKILSRGSLSSHKGLNGACSVHEYTGTFAGQPVRFKMTSVCGHVMTLDFLGKYNKWDKVDPAELFSQAPTEKKEANPKLNMVKFLQVEGRGCDYIVLWLDCDKEGENICFEVLDAVLPVMNKAHGGEKTVFRARFSSITDTDICNAMACLGEPDHNEALSVDARQELDLRIGCAFTRFQTKYFQGKYGDLDSSLISFGPCQTPTLGFCVERHDKIQSFKPETYWVLQAKVNTDKDRSLLLDWDRVRVFDREIAQMFLNMTKLEKEAQVEATSRKEKAKQRPLALNTVEMLRVASSSLGMGPQHAMQTAERLYTQGYISYPRTETTHYPENFDLKGSLRQQANHPYWADTVKRLLAEGINRPRKGHDAGDHPPITPMKSATEAELGGDAWRLYEYITRHFIATVSHDCKYLQSTISFRIGPELFTCSGKTVLSPGFTEVMPWQSVPLEESLPTCQRGDAFPVGEVKMLEKQTNPPDYLTEAELITLMEKHGIGTDASIPVHINNICQRNYVTVESGRRLKPTNLGIVLVHGYYKIDAELVLPTIRSAVEKQLNLIAQGKADYRQVLGHTLDVFKRKFHYFVDSIAGMDELMEVSFSPLAATGKPLSRCGKCHRFMKYIQAKPSRLHCSHCDETYTLPQNGTIKLYKELRCPLDDFELVLWSSGSRGKSYPLCPYCYNHPPFRDMKKGMGCNECTHPSCQHSLSMLGIGQCVECESGVLVLDPTSGPKWKVACNKCNVVAHCFENAHRVRVSADTCSVCEAALLDVDFNKAKSPLPGDETQHMGCVFCDPVFQELVELKHAASCHPMHRGGPGRRQGRGRGRARRPPGKPNPRRPKDKMSALAAYFV
Proteomes:
UP000005640

Function

Function:
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 (By similarity). Possesses negatively supercoiled DNA relaxing activity.
Catalytic Activity:
ATP-independent breakage of single-stranded DNA, followed by passage and rejoining.
Active Site:
ACT_SITE 336 336 O-(5'-phospho-DNA)-tyrosine intermediate.
Gene Ontology Go:
condensed chromosome
nucleus
DNA binding
DNA topoisomerase activity
DNA topoisomerase type I activity
poly(A) RNA binding
chromosome segregation
DNA topological change
Gene Ontology Biological Process:
chromosome segregation
DNA topological change
Gene Ontology Molecular Function:
DNA binding
DNA topoisomerase activity
DNA topoisomerase type I activity
poly(A) RNA binding
Gene Ontology Cellular Component:
condensed chromosome
nucleus
Keywords:
Alternative splicing
Complete proteome
DNA-binding
Isomerase
Polymorphism
Reference proteome
Topoisomerase
Interacts With:
Q6UY14-3; Q9UJV3-2; Q9UL42; Q7Z698; Q9Y2D8; Q8WV44

Publication

PubMed ID:
9927731 9074928 15461802 15489334