TK1
Description
The TK1 (thymidine kinase 1) is a protein-coding gene located on chromosome 17.
TK1 is a human thymidine kinase with two forms: cytosolic and mitochondrial. The cytosolic form is highly active in proliferating cells, peaking during the S phase of the cell cycle and being very low in resting cells. TK1 interacts with P21. Elevated serum TK-1 levels are associated with the return of breast and other cancers, making it a potential marker for early cancer detection, staging, and recurrence monitoring. TK-1 activity can be measured using enzyme assays or immunoassays.
TK1 is a cell-cycle regulated enzyme involved in nucleotide metabolism (PubMed:9575153). It catalyzes the first step in the salvage pathway, converting thymidine into thymidine monophosphate (PubMed:22385435). Its expression is regulated transcriptionally, limiting it to the S phase of the cell cycle. This transient expression coincides with the oscillation in intracellular dTTP concentration (Probable). TK1 is also important for the activation of anticancer and antiviral nucleoside analog prodrugs such as 1-b-d-arabinofuranosylcytosine (AraC) and 3c-azido-3c-deoxythymidine (AZT) (PubMed:22385435). {ECO:0000269|PubMed:22385435, ECO:0000269|PubMed:9575153, ECO:0000305|PubMed:17407781}
TK1 is also known as TK2.
