TOP1MT: Mitochondrial Topoisomerase I
A key enzyme for mitochondrial DNA replication and transcription, implicated in mitochondrial disorders and cancer.
Gene Information Card
| Symbol | TOP1MT |
|---|---|
| Full Name | DNA topoisomerase I mitochondrial |
| Gene Type | Protein coding |
| Chromosomal Location | 8q24.3 |
| NCBI Gene ID | 116447 ncbi.nlm.nih.gov/gene/116447 |
| Ensembl ID | ENSG00000198890 |
| UniProt ID | Q969P6 |
| OMIM ID | 609267 |
| HGNC ID | 23786 |
| Aliases | TOP1mt, MTOP1 |
Description
TOP1MT encodes a mitochondrial DNA topoisomerase I that relaxes supercoiled mitochondrial DNA (mtDNA) during replication and transcription. It is essential for maintaining mtDNA integrity and copy number. The enzyme is localized to the mitochondria and is distinct from the nuclear topoisomerase I (TOP1).
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Mitochondrial DNA depletion syndrome | Loss-of-function mutations reduce mtDNA copy number | PMID: 21741921 |
| Hepatocellular carcinoma | Overexpression linked to increased mtDNA replication and tumor growth | PMID: 25642768 |
| Breast cancer | Altered expression associated with mtDNA instability | PMID: 28397838 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Heart | 12.5 | Medium |
| Liver | 8.3 | Medium |
| Skeletal muscle | 6.7 | Low |
| Brain | 4.2 | Low |
| Kidney | 9.1 | Medium |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 15.2 | Cervical cancer cell line |
| HepG2 | 11.8 | Hepatocellular carcinoma cell line |
| MCF7 | 9.5 | Breast cancer cell line |
| A549 | 7.3 | Lung cancer cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.136C>T (p.Arg46Trp) | Missense | Rare | Reduced catalytic activity |
| c.502A>G (p.Lys168Glu) | Missense | Rare | Impaired mitochondrial localization |
| c.784_785del (p.Lys262Glufs*2) | Frameshift | Very rare | Loss of function |
Mutation functional classification
Loss of Function (LOF)
Mutations that reduce or abolish topoisomerase activity, leading to mtDNA depletion.
Gain of Function (GOF)
Not reported.
Dominant Negative (DN)
Not reported.
View complete mutation data：
Gene Ontology (GO)
| • DNA topoisomerase type I activity | • Mitochondrion |
| • DNA replication | • DNA topological change |
| • Mitochondrial DNA replication |
Pathways
• Mitochondrial DNA replication
• Mitochondrial transcription
Protein Summary
TOP1MT is a 601-amino acid protein that catalyzes the relaxation of supercoiled mtDNA. It contains a mitochondrial targeting sequence and a conserved topoisomerase domain. The enzyme is essential for mtDNA replication and transcription, and its dysfunction is linked to mitochondrial diseases and cancer.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| TOP1MT Knockout HEK293 Cell Line | EDJ-KQ7570 | Human | 116447 | Details Get a Quote |
| TOP1MT Knockout A-549 Cell Line | EDJ-KQ31533 | Human | 116447 | Details Get a Quote |
| TOP1MT Knockout HCT 116 Cell Line | EDJ-KQ32880 | Human | 116447 | Details Get a Quote |
| TOP1MT Knockout HeLa Cell Line | EDJ-KQ32881 | Human | 116447 | Details Get a Quote |
