TOP3B Antibody – Rabbit

This gene encodes a DNA topoisomerase, an enzyme that controls and alters the topologic states of DNA during transcription. This enzyme catalyzes the transient breaking and rejoining of a single strand of DNA which allows the strands to pass through one another, thus relaxing the supercoils and altering the topology of DNA. The enzyme interacts with DNA helicase SGS1 and plays a role in DNA recombination, cellular aging and maintenance of genome stability. Alternative splicing of the C-terminus of this gene results in three transcript variants which have distinct tissue specificity; however, not all variants have been fully described. [provided by RefSeq, Jul 2008]

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. 3 isoforms of the human protein are produced by alternative splicing.

Protein type: EC 5.99.1.2; DNA-binding; Topoisomerase

Chromosomal Location of Human Ortholog: 22q11.22

Cellular Component: nucleoplasm; condensed chromosome; nucleus

Molecular Function: DNA binding; DNA topoisomerase activity; DNA topoisomerase type I activity

Biological Process: DNA topological change; chromosome segregation