Seroatlas · Human Serome Atlas

TK1

Thymidine kinase, cytosolic

Also known as: KITH_HUMAN

Cross-references: UniProt · Ensembl · Human Protein Atlas · GeneCards · NCBI Gene

Protein identityUniProt · HPA

UniProt accession: P04183
Gene: TK1
Ensembl: ENSG00000167900
Chromosome: 17
Canonical length: 234 aa
Protein class: Cancer-related genes, Enzymes, Metabolic proteins, Plasma proteins, Predicted intracellular proteins
Quaternary structure: Homotetramer

OverviewNCBI Gene

The protein encoded by this gene is a cytosolic enzyme that catalyzes the addition of a gamma-phosphate group to thymidine. This creates dTMP and is the first step in the biosynthesis of dTTP, which is one component required for DNA replication. The encoded protein, whose levels fluctuate depending on the cell cycle stage, can act as a low activity dimer or a high activity tetramer. High levels of this protein have been used as a biomarker for diagnosing and categorizing many types of cancers. [provided by RefSeq, Oct 2016]

Canonical amino-acid sequenceUniProt

234 residues, UniProt reviewed canonical sequence.

>P04183|TK1
     1  MSCINLPTVL PGSPSKTRGQ IQVILGPMFS GKSTELMRRV RRFQIAQYKC LVIKYAKDTR
    61  YSSSFCTHDR NTMEALPACL LRDVAQEALG VAVIGIDEGQ FFPDIVEFCE AMANAGKTVI
   121  VAALDGTFQR KPFGAILNLV PLAESVVKLT AVCMECFREA AYTKRLGTEK EVEVIGGADK
   181  YHSVCRLCYF KKASGQPAGP DNKENCPVPG KPGEAVAARK LFAPQQILQC SPAN

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against TK1 can act on the native protein depends on physical access: surface and secreted proteins are reachable by circulating antibodies, intracellular proteins usually are not.

Antibody reachability: Intracellular
Secreted: No
Transmembrane segments: 0
Mean surface accessibility (rSASA): 0.37
Highest tissue expression: 73 nTPM

Expression across tissuesHPA

Tissue

bone marrow: 73 nTPM
lymph node: 32 nTPM
esophagus: 30 nTPM
tonsil: 29 nTPM
thymus: 23 nTPM
colon: 23 nTPM

Single-cell type

extravillous trophoblasts: 249 nCPM
esophageal basal cells: 188 nCPM
migrating cytotrophoblasts: 186 nCPM
enteric transient amplifying cells: 144 nCPM
erythrocyte progenitors: 110 nCPM
gastric progenitor cells: 101 nCPM

Immune cell

T-reg: 34 nTPM
NK-cell: 11 nTPM
memory CD4 T-cell: 8 nTPM
memory B-cell: 5.8 nTPM
total PBMC: 5.5 nTPM
memory CD8 T-cell: 4 nTPM

Brain region

white matter: 7.4 nTPM
thalamus: 7 nTPM
cerebellum: 6.1 nTPM
basal ganglia: 5.7 nTPM
cerebral cortex: 5.7 nTPM
medulla oblongata: 5.7 nTPM

ReferencesPubMed · IEDB

Publications for TK1 from three distinct lines of evidence, kept separate because they answer different questions: whether antibodies are directed at the protein, whether a B-cell epitope has been mapped on it, and whether a T-cell epitope has. Each is labelled with its source.

Reference: AutoantibodyPubMed

2 publications

Serum thymidine kinase 1 protein concentrations and presence of its autoantibody as biomarkers for screening dogs with malignant tumors.
2024 · J Vet Intern Med · RCR 1.9 · 4 citations
Use of thymidine kinase 1 autoantibody, thymidine kinase antigen, extracellular protein kinase A autoantibody, and C-reactive protein for early detection of malignant tumors in dogs.
2025 · J Vet Intern Med · 2 citations

Sources: PubMed — antigen-level antibody evidence from a custom retrieval. Records matching a controlled set of autoantibody terms (the MeSH descriptors Autoantibodies and Autoantigens, with title and abstract term variants) were obtained through NCBI E-utilities, and their titles and abstracts parsed for constructions that direct an antibody at a named protein rather than for co-occurrence. Captured names were resolved against UniProt nomenclature and each antigen adjudicated individually against the source text. Bibliographic records from PubMed and MeSH, U.S. National Library of Medicine; citation metrics from NIH iCite (Hutchins et al., PLoS Biology 2016). Titles link to PubMed; abstracts are not reproduced here. The NLM does not endorse this analysis.

Genetic constraint and essentialitygnomAD · DepMap

Does the body need this protein intact? Low LOEUF or a strong DepMap dependency means loss or blockade of the protein is likely to be felt.

gnomAD LOEUF (loss-of-function intolerance): 0.78
gnomAD pLI: 0.14
gnomAD missense Z: 1.31
DepMap mean gene effect: -0.15
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 7% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

nucleobase-containing compound metabolic process
protein homotetramerization
thymidine biosynthetic process
thymidine metabolic process
DNA synthesis involved in mitotic DNA replication

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

P-loop containing nucleoside triphosphate hydrolase
Thymidine kinase
Thymidine kinase, conserved site
Thymidine kinase

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of TK1 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads TK1 as an antibody target. Whether an autoantibody or antibody against TK1 could matter depends on whether native TK1 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

TK1 is annotated as predominantly intracellular. Intracellular proteins are common autoantibody markers, becoming visible to the immune system after cell injury or altered processing, but are usually markers of disease rather than direct drivers.

Annotation status

The present source text does not explicitly label TK1 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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