Editing Kinase (section)

===Thymidine kinase===
{{main|Thymidine kinase}}
[[Thymidine kinase]] is one of the many nucleoside kinases that are responsible for nucleoside phosphorylation. It phosphorylates [[thymidine]] to create [[thymidine monophosphate]] (dTMP). This kinase uses an ATP molecule to supply the [[phosphate]] to thymidine, as shown below. This transfer of a phosphate from one nucleotide to another by thymidine kinase, as well as other nucleoside and nucleotide kinases, functions to help control the level of each of the different nucleotides.

[[File:Thymidine kinase.png|thumb|center|upright=2.5|Overall reaction catalysed by thymidine kinase.]]

After creation of the dTMP molecule, another kinase, [[thymidylate kinase]], can act upon dTMP to create the [[thymidine diphosphate|diphosphate]] form, dTDP. [[Nucleoside-diphosphate kinase|Nucleoside diphosphate kinase]] catalyzes production of [[thymidine triphosphate]], dTTP, which is used in [[DNA synthesis]]. Because of this, thymidine kinase activity is closely correlated with the [[cell cycle]] and used as a [[tumor marker]] in [[Thymidine kinase in clinical chemistry|clinical chemistry]].<ref>{{cite journal | vauthors = Aufderklamm S, Todenhöfer T, Gakis G, Kruck S, Hennenlotter J, Stenzl A, Schwentner C | title = Thymidine kinase and cancer monitoring | journal = Cancer Letters | volume = 316 | issue = 1 | pages = 6–10 | date = March 2012 | pmid = 22068047 | doi = 10.1016/j.canlet.2011.10.025 }}</ref> Therefore, it can sometime be used to predict patient prognosis.<ref>{{cite journal | vauthors = Topolcan O, Holubec L | title = The role of thymidine kinase in cancer diseases | journal = Expert Opinion on Medical Diagnostics | volume = 2 | issue = 2 | pages = 129–141 | date = February 2008 | pmid = 23485133 | doi = 10.1517/17530059.2.2.129 }}</ref> Patients with mutations in the thymidine kinase [[gene]] may have a certain type of [[mitochondrial DNA]] depletion [[syndrome]], a disease that leads to death in early childhood.<ref>{{cite journal | vauthors = Götz A, Isohanni P, Pihko H, Paetau A, Herva R, Saarenpää-Heikkilä O, Valanne L, Marjavaara S, Suomalainen A | display-authors = 6 | title = Thymidine kinase 2 defects can cause multi-tissue mtDNA depletion syndrome | journal = Brain | volume = 131 | issue = Pt 11 | pages = 2841–2850 | date = November 2008 | pmid = 18819985 | doi = 10.1093/brain/awn236 | doi-access = free }}</ref>