TAF1A RNA Polymerase I, TATA Box Binding Protein (TBP)-Associated Factor
A core component of the RNA polymerase I transcription initiation complex, essential for ribosomal RNA synthesis.
Gene Information Card
| Symbol | TAF1A |
|---|---|
| Full Name | TATA-box binding protein associated factor, RNA polymerase I subunit A |
| Gene Type | protein-coding |
| Chromosomal Location | 1q42.13 |
| NCBI Gene ID | 9015 ncbi.nlm.nih.gov/gene/9015 |
| Ensembl ID | ENSG00000143178 |
| UniProt ID | Q15573 |
| OMIM ID | 604783 |
| HGNC ID | 11533 |
| Aliases | TAFI-110, TAFI110, TAF1A, SL1, TAFI110, TAFI-110 |
Description
TAF1A encodes a component of the transcription factor SL1 (selectivity factor 1) complex, which is required for RNA polymerase I-mediated transcription of ribosomal RNA genes. The protein directly interacts with the TATA box-binding protein (TBP) and other SL1 subunits to nucleate pre-initiation complex formation at the ribosomal DNA promoter. TAF1A is essential for ribosome biogenesis and cell growth.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Colorectal cancer | Overexpression of TAF1A may drive rRNA synthesis and cell proliferation; altered expression linked to tumorigenesis. | COSMIC; PMID: 24623306 |
| Hepatocellular carcinoma | TAF1A upregulation correlates with poor prognosis; promotes rRNA transcription and cell cycle progression. | PMID: 31525674 |
| Ribosomopathy (general) | Dysregulation of RNA polymerase I transcription factors, including TAF1A, can impair ribosome assembly and cause developmental disorders. | OMIM; PMID: 21930510 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 28.5 | High |
| Lymph node | 22.3 | High |
| Bone marrow | 20.1 | High |
| Brain (cerebellum) | 15.7 | Medium |
| Liver | 12.4 | Medium |
| Heart | 8.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 25.1 | Cervical carcinoma; high expression |
| HEK293 | 22.8 | Embryonic kidney; moderate-high |
| K562 | 19.4 | Leukemia; moderate |
| HepG2 | 17.6 | Hepatocellular carcinoma; moderate |
| A549 | 14.3 | Lung carcinoma; moderate |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1123G>A (p.Gly375Arg) | Missense | <0.01% (gnomAD) | Unknown functional impact; rare population variant |
| c.1567C>T (p.Arg523Trp) | Missense | <0.01% (gnomAD) | Predicted damaging (SIFT, PolyPhen); not validated in disease |
| c.2014_2015insA (p.Thr672Asnfs*3) | Frameshift | <0.01% (COSMIC) | Loss-of-function; observed in colorectal cancer sample |
Mutation functional classification
Loss of Function (LOF)
Frameshift mutations (e.g., p.Thr672Asnfs*3) are predicted to truncate the protein and abolish SL1 complex assembly, impairing rRNA transcription.
Gain of Function (GOF)
No confirmed gain-of-function mutations reported in TAF1A.
Dominant Negative (DN)
No dominant-negative mutations described; however, missense changes in the TBP-binding domain could theoretically interfere with complex formation.
View complete mutation data：
Gene Ontology (GO)
| • RNA polymerase I transcription regulator complex | • transcription initiation at RNA polymerase I promoter |
| • DNA binding | • protein heterodimerization activity |
| • nucleolus | • ribosome biogenesis |
Pathways
• RNA polymerase I transcription (Reactome: R-HSA-73728)
• rRNA processing (Reactome: R-HSA-72312)
• Gene expression (transcription) (Reactome: R-HSA-74160)
Protein Summary
TAF1A is a 110 kDa protein that localizes to the nucleolus and is a core component of the SL1 complex. It contains a conserved TBP-binding domain and a C-terminal region required for interaction with other SL1 subunits. The protein is essential for recruiting RNA polymerase I to ribosomal DNA promoters and for initiating transcription of pre-ribosomal RNA. Post-translational modifications, including phosphorylation, regulate its activity and stability.
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