Monoclonal Anti-Topoisomerase I (mouse IgG1 isotype) is derived from the Mab1 hybridoma produced by the fusion of SP2/0 mouse myeloma cells and splenocytes from BALB/c mice immunized with human purified topoisomerase I. The protein family of DNA topoisomerases is divided into two types (type I and II). The type I enzymes include eukaryotic and bacterial topoisomerase I and III. Human DNA Topoisomerase I belong to the subtype IB enzymes. The protein has four distinct domains. There are four nuclear localization signals in the N-terminal domain. A linker domain of 77 amino acids follows the core domain. The fourth domain, which is 53 amino acids long, contains the active site Tyr723. Topoisomerase I (TOP1) gene is located on human chromosome 20q12.
DNA topoisomerases are enzymes that control the amount of supercoiling in DNA. Without topoisomerases, DNA cannot replicate normally. Type I enzymes of DNA topoisomerases introduce transient single strand breaks in DNA. Recently it was reported that DNA topoisomerase I is involved in modulation of RNA and is present in retroviral particles, like human immunodeficiency virus (HIV1). Furthermore, the enzyme enhances HIV-1 cDNA production in reverse transcription assays in vitro. Topoisomerase I (TOP1) serves as swivel at the time of replication, transcription and recombination, which helps in releasing over winding of duplex DNA.
