這個基因編碼一種DNA拓撲異構酶，這種酶在轉錄過程中控制和改變DNA的拓撲狀態。這種核酶參與諸如染色體凝聚、染色單體分離以及DNA轉錄和復制過程中發生的扭轉應力的減輕等過程。它催化雙鏈DNA的兩條鏈的瞬間斷裂和重新結合，使雙鏈彼此穿過，從而改變DNA的拓撲結構。這種酶有兩種形式，可能是基因復制事件的產物。編碼這種形式的基因α定位于17號染色體，β基因定位于3號染色體。編碼這種酶的基因作為幾種抗癌藥物的靶點，并且這種基因的多種突變與耐藥性的發展有關。這種酶活性的降低也可能在共濟失調毛細血管擴張癥中起作用。
This gene encodes a DNA topoisomerase, an enzyme that controls and alters the topologic states of DNA during transcription. This nuclear enzyme is involved in processes such as chromosome condensation, chromatid separation, and the relief of torsional stress that occurs during DNA transcription and replication. It catalyzes the transient breaking and rejoining of two strands of duplex DNA which allows the strands to pass through one another, thus altering the topology of DNA. Two forms of this enzyme exist as likely products of a gene duplication event. The gene encoding this form, alpha, is localized to chromosome 17 and the beta gene is localized to chromosome 3. The gene encoding this enzyme functions as the target for several anticancer agents and a variety of mutations in this gene have been associated with the development of drug resistance. Reduced activity of this enzyme may also play a role in ataxia-telangiectasia.