CTU1 (Cytosolic Thiouridylase Subunit 1)
A key enzyme in tRNA thiolation, linked to mitochondrial dysfunction and cancer metabolism.
Gene Information Card
| Symbol | CTU1 |
|---|---|
| Full Name | Cytosolic Thiouridylase Subunit 1 |
| Gene Type | Protein coding |
| Chromosomal Location | 19q13.32 |
| NCBI Gene ID | 90353 ncbi.nlm.nih.gov/gene/90353 |
| Ensembl ID | ENSG00000105329 |
| UniProt ID | Q9NZB8 |
| OMIM ID | 617202 |
| HGNC ID | 28006 |
| Aliases | NCS6, ATPBD3, FLJ20331 |
Description
CTU1 encodes a subunit of the cytosolic thiouridylase complex, which catalyzes the 2-thiolation of the wobble uridine (U34) in tRNA(Lys, Glu, Gln). This modification is critical for accurate codon-anticodon pairing and translational fidelity. CTU1 interacts with CTU2 to form the active enzyme, and its dysfunction impairs mitochondrial translation and cellular energy metabolism.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Mitochondrial complex I deficiency | Impaired tRNA thiolation leads to defective mitochondrial translation and respiratory chain assembly. | ClinVar; PMID: 24652937 |
| Colorectal cancer | CTU1 overexpression correlates with poor prognosis; altered tRNA modification may promote translational reprogramming. | COSMIC; PMID: 31570833 |
| Hepatocellular carcinoma | CTU1 upregulation linked to increased proliferation and metastasis via mTOR signaling. | COSMIC; PMID: 32747438 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 12.5 | Medium |
| Kidney | 10.2 | Medium |
| Heart | 8.7 | Medium |
| Brain | 6.1 | Low |
| Testis | 15.3 | High |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 14.0 | Embryonic kidney cells |
| HepG2 | 16.5 | Hepatocellular carcinoma |
| K562 | 9.8 | Leukemia |
| HeLa | 11.2 | Cervical adenocarcinoma |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense | Rare | Loss of start codon; likely loss of function |
| c.335G>A (p.Arg112Gln) | Missense | 0.01% | Reduced thiouridylase activity; associated with mitochondrial disease |
| c.502C>T (p.Arg168Trp) | Missense | 0.005% | Impaired CTU1-CTU2 interaction; dominant negative effect suspected |
Mutation functional classification
Loss of Function (LOF)
p.Met1? and p.Arg112Gln reduce or abolish enzymatic activity, impairing tRNA thiolation and mitochondrial translation.
Gain of Function (GOF)
No evidence of gain-of-function mutations in CTU1.
Dominant Negative (DN)
p.Arg168Trp may disrupt complex assembly, interfering with wild-type CTU1 function.
View complete mutation data：
Gene Ontology (GO)
| • tRNA wobble position uridine thiolation (GO:0002143) | • cytoplasm (GO:0005737) |
| • ATP binding (GO:0005524) | • nucleotidyltransferase activity (GO:0016779) |
| • mitochondrial translation (GO:0032543) |
Pathways
• tRNA modification in the nucleus and cytosol (R-HSA-6782315)
• Mitochondrial translation (R-HSA-5389840)
• Sulfur relay system (R-HSA-2408557)
Protein Summary
CTU1 is a 45 kDa cytoplasmic protein that, together with CTU2, forms the 2-thiouridylase complex. It contains an ATP-binding domain and a catalytic cysteine residue essential for sulfur transfer. The protein is ubiquitously expressed with highest levels in testis and liver. Defects in CTU1 lead to impaired wobble uridine modification, causing mitochondrial dysfunction and altered translation of nuclear-encoded mitochondrial genes.
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