Table 4.
Human DNA helicases
| S. No. | Name of helicase | Mol. mass (kDa) | Nucleotide cofactors | Remarks |
|---|---|---|---|---|
| 1. | HDH I | 65 | ATP, dATP | First human DNA helicase reported in purified form and also functions as RNA helicase. |
| 2. | HDH II/Ku | 72, 87 | ATP, dATP | DNA end binding protein and involved in dsDNA break repair. |
| 3. | HDH III | 46 | ATP, dATP | Stimulated by fork-like structure of substrates. |
| 4. | HDH IV | 100 | ATP, dATP | Can also function as RNA helicase. |
| 5. | HDH V | 92 | ATP, dATP | Has highest turn over rate. |
| 6. | HDH VI | 128 | ATP, dATP | Stimulated by fork-like structure of substrates |
| 7. | HDH VII | 36 | nd | Trimer of one molecule of hnRNP A1 and two molecules of annexin II |
| 8. | HDH VIII | 68 | ATP | Functions both as DNA and RNA helicase. |
| 9. | HDH IX | 45 | nd | It is a Gly Arg rich protein. |
| 10. | XPD/ERCC2 | 87 | ATP, dATP | Functions in nucleotide excision repair; component of BTF2-TFIIH transcription factor. |
| 11. | XPB/ERCC3 | 89 | ATP | Functions in nucleotide excision repair; component of BTF2-TFIIH transcription factor. |
| 12. | Helicase ε | 72 | ATP, dATP, CTP | Helicase activity is dependent on HRP-A. |
| 13. | Helicase ∝ | 110 | ATP, dATP, | Stimulated by 5′-tailed fork and SSB. |
| 90 | CTP, dCTP | |||
| 14. | RIP 100 | 100 | ATP, dATP | Associated with RIP60 protein. |
| 15. | Helicase Q1 | 73 | ATP, dATP | Gene homologous to E. coli RecQ gene. |
| 16. | Helicase Q2 | 100 | ATP | Identical to DNA helicase IV. |
| 17. | HchlR1 | 112 | ATP | Can unwind RNA/DNA substrates. |
| 18. | HhcsA | 116 | ATP, dATP | Hexameric protein. |
| 19. | WRN helicase | 163 | ATP, dATP> | Mutated in Werner syndrome, homologous to RecQ and contains 3′–5′ exonuclease activity. |
| dCTP, CTP | ||||
| 20. | BLM helicase | ∼160 | ATP | Mutated in cells of Blooms syndrome patient and belongs to RecQ family. |
| 21. | Mcm4/6/7 complex | ∼600 | ATP, dATP | Stimulated by SSB and forked DNA structures; can function as a replication helicase. |
| 22. | HEL308 | 124.5 | ATP, dATP | Stimulated by RPA. |
| 23. | hFBH1 | ∼120 | ATP | First F-box protein with helicase activity. |
| 24 | Human RECQ1 | 75 | ATP | Stimulated by hRPA and can also unwind blunt end substrate with bubble of 25 nt. |
| 25 | BACH1 | 130 | ATP | Involved in dsDNA break repair. |