Domain Annotation: SCOP2 Classification SCOP2 Database Homepage

ChainsTypeFamily Name Domain Identifier Family IdentifierProvenance Source (Version)
ASCOP2B SuperfamilyP-loop nucleotide/nucleoside kinase-like 8019153 3002021 SCOP2B (2022-06-29)
BSCOP2B SuperfamilyP-loop nucleotide/nucleoside kinase-like 8019153 3002021 SCOP2B (2022-06-29)

Domain Annotation: ECOD Classification ECOD Database Homepage

ChainsFamily NameDomain Identifier ArchitecturePossible HomologyHomologyTopologyFamilyProvenance Source (Version)
AHerpes_TKe1kimA1 A: a/b three-layered sandwichesX: P-loop domains-likeH: P-loop domains-relatedT: P-loop containing nucleoside triphosphate hydrolasesF: Herpes_TKECOD (1.6)
BHerpes_TKe1kimB1 A: a/b three-layered sandwichesX: P-loop domains-likeH: P-loop domains-relatedT: P-loop containing nucleoside triphosphate hydrolasesF: Herpes_TKECOD (1.6)

Domain Annotation: CATH CATH Database Homepage

Protein Family Annotation Pfam Database Homepage

ChainsAccessionNameDescriptionCommentsSource
A, B
PF00693Thymidine kinase from herpesvirus (Herpes_TK)Thymidine kinase from herpesvirus- Domain

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

ChainsPolymerMolecular FunctionBiological ProcessCellular Component
A, B
THYMIDINE KINASE -

InterPro: Protein Family Classification InterPro Database Homepage

Structure Motif Annotation: Mechanism and Catalytic Site Atlas M-CSA Database Homepage

ChainsEnzyme NameDescriptionCatalytic Residues
thymidine kinase  M-CSA #588

Thymidine kinases (TK) are key enzymes in the pyrimidine salvage pathway catalyzing the phosphate transfer from ATP to thymidine (dT) in the presence of Mg2+ and thus, yielding thymidine monophosphate (dTMP) and ADP. Herpesviridae, such as Herpes simplex virus type 1, encode for their own, multifunctional TK. Unlike the very specific human cytosolic TK (TK1), it is able to phosphorylate pyrimidine as well as purine analogs and demands less stereochemical restrictions concerning the sugar moiety also accepting acyclic side chains as phosphate acceptors (e.g., aciclovir). Therefore, the difference in substrate specificity of human TK 1 and TKHSV1 is a crucial point in establishing a molecular basis for selective antiviral therapy, featuring TKHSV1 as the center of activation of antiviral drugs such as aciclovir (ACV), penciclovir, and ganciclovir (GCV). First being activated by phosphorylation by viral encoded TK, these nucleoside analogs in their triphosphate form block the viral replication by subsequently terminating DNA elongation at the viral DNA polymerase. In combination with GCV TKHSV1 is an established tool used as a prodrug-activating enzyme, so-called suicide enzyme, in gene therapy of cancer, AIDS, and in controlling graft-versus-host disease by allogenic bone marrow transplant (allo BMT).

Defined by 7 residues: LYS:A-52 [auth A-62]GLU:A-73 [auth A-83]ASP:A-152 [auth A-162]ARG:A-153 [auth A-163]ARG:A-210 [auth A-220]ARG:A-212 [auth A-222]GLU:A-215 [auth A-225]
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