TOP3A gene

DNA topoisomerase III alpha

The information on this page was automatically extracted from online scientific databases.

From NCBI Gene:

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 reducing the number of supercoils and altering the topology of DNA. This enzyme forms a complex with BLM which functions in the regulation of recombination in somatic cells. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Mar 2016]

From UniProt:

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 then 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. As an essential component of the RMI complex it is involved in chromosome separation and the processing of homologous recombination intermediates to limit DNA crossover formation in cells. Has DNA decatenation activity (PubMed:30057030). It is required for mtDNA decatenation and segregation after completion of replication, in a process that does not require BLM, RMI1 and RMI2 (PubMed:29290614).

From NCBI Gene:


From UniProt:

Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 5 (PEOB5): A form of progressive external ophthalmoplegia, a mitochondrial myopathy characterized by progressive paralysis of the levator palpebrae, orbicularis oculi, and extraocular muscles. PEOB5 features include slowly progressive ptosis, intermittent double vision, cardiac arrhythmias, exercise intolerance, proximal limb and neck muscle weakness, and cerebellar ataxia. Patients skeletal muscle biopsy show numerous COX-deficient ragged-red fibers, increased mtDNA deletions, and extensive variable mtDNA rearrangements. [MIM:618098]

Microcephaly, growth restriction, and increased sister chromatid exchange 2 (MGRISCE2): An autosomal recessive disorder characterized by intrauterine growth restriction, poor postnatal growth with short stature and microcephaly, and increased sister chromatid exchange on cell studies. [MIM:618097]

Cytogenetic Location: 17p11.2, which is the short (p) arm of chromosome 17 at position 11.2

Molecular Location: base pairs 18,269,958 to 18,314,996 on chromosome 17 (Homo sapiens Updated Annotation Release 109.20200522, GRCh38.p13) (NCBI)

Cytogenetic Location: 17p11.2, which is the short (p) arm of chromosome 17 at position 11.2
  • PEOB5
  • TOP3
  • ZGRF7