Topoisomerase I (TOP1) Antibody – Rabbit Polyclonal

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 altering the topology of DNA. This gene is localized to chromosome 20 and has pseudogenes which reside on chromosomes 1 and 22. [provided by RefSeq, Jul 2008]

TOP1: 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-(3'-phosphotyrosyl)-enzyme intermediate and the expulsion of a 5'-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 5'-OH attacks the covalent intermediate to expel the active-site tyrosine and restore the DNA phosphodiester backbone. Regulates the alternative splicing of tissue factor (F3) pre-mRNA in endothelial cells. A chromosomal aberration involving TOP1 is found in a form of therapy-related myelodysplastic syndrome. Translocation t(11;20)(p15;q11) with NUP98. Belongs to the type IB topoisomerase family.

Protein type: EC 5.99.1.2; Isomerase; Nucleolus; Oncoprotein

Chromosomal Location of Human Ortholog: 20q12

Cellular Component: DNA topoisomerase complex (ATP-hydrolyzing); fibrillar center; nuclear chromosome; nucleolus; nucleoplasm; nucleus; P-body; perikaryon

Molecular Function: ATP binding; chromatin binding; DNA binding; DNA topoisomerase type I activity; double-stranded DNA binding; protein binding; protein domain specific binding; protein serine/threonine kinase activity; RNA binding; single-stranded DNA binding

Biological Process: chromatin remodeling; chromosome segregation; circadian regulation of gene expression; circadian rhythm; DNA replication; DNA topological change; embryonic cleavage; peptidyl-serine phosphorylation; phosphorylation; programmed cell death; protein sumoylation; response to drug; viral process