Thymidine kinase
Thymidine kinase (TK) is an enzyme that is found in most living organisms. It plays a crucial role in the DNA replication process, as it is responsible for the phosphorylation of thymidine, a nucleoside that is one of the building blocks of DNA.
Function[edit | edit source]
Thymidine kinase catalyzes the transfer of a phosphate group from adenosine triphosphate (ATP) to thymidine, producing thymidine monophosphate (TMP) and adenosine diphosphate (ADP). This reaction is a key step in the salvage pathway, a method of recycling nucleosides produced during DNA replication and repair.
Structure[edit | edit source]
Thymidine kinase exists in two forms: TK1 and TK2. TK1 is a cytosolic enzyme that is active during the S phase of the cell cycle, while TK2 is a mitochondrial enzyme that is active throughout the cell cycle. Both forms of the enzyme are homodimers, meaning they consist of two identical subunits.
Clinical significance[edit | edit source]
Thymidine kinase is a target for antiviral drugs, such as acyclovir, which is used to treat herpes simplex virus infections. The enzyme is also a useful biomarker for certain types of cancer, as its activity is often elevated in cancer cells.
See also[edit | edit source]
- DNA replication
- Nucleoside
- Phosphate group
- Adenosine triphosphate
- Thymidine monophosphate
- Adenosine diphosphate
- Salvage pathway
- Cell cycle
- Herpes simplex virus
- Biomarker
- Cancer
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Template:Virology Template:Oncology
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