Non-homologous end joining
Non-homologous End Joining[edit | edit source]
Non-homologous end joining (NHEJ) is a pathway that repairs double-strand breaks (DSBs) in DNA. It is one of the two major pathways for repairing DSBs, the other being homologous recombination. NHEJ is considered a more error-prone repair mechanism compared to homologous recombination because it does not require a homologous template and can result in the loss or gain of nucleotides at the break site.
Mechanism[edit | edit source]
NHEJ involves several key steps and proteins that facilitate the repair of DNA double-strand breaks:
Recognition and Binding[edit | edit source]
The process begins with the recognition of the DSB by the Ku protein complex, which consists of Ku70 and Ku80 subunits. This complex binds to the DNA ends and protects them from degradation.
Processing of DNA Ends[edit | edit source]
Once bound, the DNA ends may require processing to make them compatible for ligation. This processing can involve the removal of damaged nucleotides or the addition of nucleotides to fill in gaps. Enzymes such as the Artemis endonuclease and the DNA polymerase _ and _ are involved in this step.
Ligation[edit | edit source]
The final step in NHEJ is the ligation of the DNA ends. This is carried out by the DNA ligase IV complex, which is recruited to the site by the XRCC4 protein. The ligase seals the DNA backbone, completing the repair process.
Importance in Cells[edit | edit source]
NHEJ is crucial for maintaining genomic stability, especially in non-dividing cells where homologous recombination is not possible. It is also important in the immune system for the generation of diversity in antibodies and T-cell receptors through a process known as V(D)J recombination.
Clinical Implications[edit | edit source]
Defects in NHEJ can lead to increased sensitivity to ionizing radiation and a predisposition to certain types of cancer. Understanding NHEJ is also important in the context of gene therapy and genome editing technologies, such as CRISPR-Cas9, where controlled induction of DSBs is used to introduce genetic changes.
Related Pages[edit | edit source]
| Excision repair | |
|---|---|
| Other forms of repair | |
| Other/ungrouped proteins | |
| Regulation | |
| Other/ungrouped | |
Search WikiMD
Ad.Tired of being Overweight? Try W8MD's physician weight loss program.
Semaglutide (Ozempic / Wegovy and Tirzepatide (Mounjaro / Zepbound) available.
Advertise on WikiMD
|
WikiMD's Wellness Encyclopedia |
| Let Food Be Thy Medicine Medicine Thy Food - Hippocrates |
Translate this page: - East Asian
中文,
日本,
한국어,
South Asian
हिन्दी,
தமிழ்,
తెలుగు,
Urdu,
ಕನ್ನಡ,
Southeast Asian
Indonesian,
Vietnamese,
Thai,
မြန်မာဘာသာ,
বাংলা
European
español,
Deutsch,
français,
Greek,
português do Brasil,
polski,
română,
русский,
Nederlands,
norsk,
svenska,
suomi,
Italian
Middle Eastern & African
عربى,
Turkish,
Persian,
Hebrew,
Afrikaans,
isiZulu,
Kiswahili,
Other
Bulgarian,
Hungarian,
Czech,
Swedish,
മലയാളം,
मराठी,
ਪੰਜਾਬੀ,
ગુજરાતી,
Portuguese,
Ukrainian
Medical Disclaimer: WikiMD is not a substitute for professional medical advice. The information on WikiMD is provided as an information resource only, may be incorrect, outdated or misleading, and is not to be used or relied on for any diagnostic or treatment purposes. Please consult your health care provider before making any healthcare decisions or for guidance about a specific medical condition. WikiMD expressly disclaims responsibility, and shall have no liability, for any damages, loss, injury, or liability whatsoever suffered as a result of your reliance on the information contained in this site. By visiting this site you agree to the foregoing terms and conditions, which may from time to time be changed or supplemented by WikiMD. If you do not agree to the foregoing terms and conditions, you should not enter or use this site. See full disclaimer.
Credits:Most images are courtesy of Wikimedia commons, and templates, categories Wikipedia, licensed under CC BY SA or similar.
Contributors: Prab R. Tumpati, MD
