Function
Thymidine kinase or deoxyribonucleoside kinase (TK) catalyzes the conversion of deoxythymidine (THM) to deoxythymidine 5’-phosphate (THMP) with the conversion of ATP to ADP. TK has an important role in the synthesis of DNA. It is required for the action of many antiviral drugs. Higher organisms have 2 isozymes. TK1 is cell cycle-dependent while TK2 [1]is found in the mitochondria and is cell cycle-independent. TK undergoes feed-back regulation by thymidine triphosphate (TTP). Adenosyl-thymidyl-tetraphosphate (TP4A) is a bisubstrate inhibitor of TK. For more details see Herpes Simplex Virus Thymidine Kinase and drug Aciclovir.
Relevance
TK1 level in serum is a marker for leukemia and lymphoma[2].
Disease
Mutations in TK2 are associated with mitochondrial DNA depletion[3].
Structural highlights
The biological assembly of Thymidine kinase is . [4]. Water molecules are shown as red spheres.
3D Structures of thymidine kinase
Thymidine kinase 3D structures