PROSITE documentation PDOC00524
Thymidine kinase cellular-type signature


Thymidine kinase (TK) (EC is an ubiquitous enzyme that catalyzes the ATP-dependent phosphorylation of thymidine. A comparison of TK sequences has shown [1,2,3] that there are two different families of TK. One family groups together TK from herpesviruses as well as cellular thymidylate kinases, while the second family currently consists of TK from the following sources:

  • Vertebrates.
  • Bacterial.
  • Bacteriophage T4.
  • Poxviruses.
  • African swine fever virus (ASF).

As a signature pattern for this family of TK we selected a conserved region which is located in the C-terminal section of these enzymes.


Proteins belonging to this family also contain a copy of the ATP/GTP- binding motif 'A' (P-loop) in their N-terminal extremity (see <PDOC00017>).

Last update:

December 2004 / Pattern and text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

TK_CELLULAR_TYPE, PS00603; Thymidine kinase cellular-type signature  (PATTERN)


1AuthorsBoyle D.B. Coupar B.E.H. Gibbs A.J. Seigman L.J. Both G.W.
TitleFowlpox virus thymidine kinase: nucleotide sequence and relationships to other thymidine kinases.
SourceVirology 156:355-365(1987).
PubMed ID3027984

2AuthorsBlasco R. Lopez-Otin C. Munoz M. Bockamp E.-O. Simon-Mateo C. Vinuela E.
TitleSequence and evolutionary relationships of African swine fever virus thymidine kinase.
SourceVirology 178:301-304(1990).
PubMed ID2389555

3AuthorsRobertson G.R. Whalley J.M.
TitleEvolution of the herpes thymidine kinase: identification and comparison of the equine herpesvirus 1 thymidine kinase gene reveals similarity to a cell-encoded thymidylate kinase.
SourceNucleic Acids Res. 16:11303-11317(1988).
PubMed ID2849761

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