TTC21B Gene
Tetratricopeptide Repeat Domain 21B
Gene Information Card
| Symbol | TTC21B |
|---|---|
| Full Name | Tetratricopeptide Repeat Domain 21B |
| Gene Type | Protein coding |
| Chromosomal Location | 2q24.3 |
| NCBI Gene ID | 79809 ncbi.nlm.nih.gov/gene/79809 |
| Ensembl ID | ENSG00000123607 |
| UniProt ID | Q8N4L2 |
| OMIM ID | 612014 |
| HGNC ID | 25603 |
| Aliases | IFT139, NPH11, SRTD4 |
Description
TTC21B encodes a protein containing tetratricopeptide repeat (TPR) domains, which is a component of the intraflagellar transport (IFT) complex A. This protein is essential for ciliary assembly and function, particularly in retrograde ciliary transport. Mutations in TTC21B cause ciliopathies including nephronophthisis and Jeune asphyxiating thoracic dystrophy.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Nephronophthisis 11 (NPH11) | Loss of function of TTC21B disrupts ciliary signaling in renal tubules, leading to cyst formation and fibrosis | ClinVar, OMIM |
| Jeune asphyxiating thoracic dystrophy (SRTD4) | Defective retrograde IFT impairs ciliary function in chondrocytes and other tissues, causing skeletal abnormalities | OMIM, PubMed |
| Ciliopathy-related renal-hepatic-pancreatic dysplasia | Biallelic TTC21B mutations impair ciliary transport in multiple organs | ClinVar |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Kidney | 12.5 | Medium |
| Testis | 8.9 | Medium |
| Lung | 6.2 | Low |
| Liver | 5.1 | Low |
| Brain | 3.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK 293 | 15.2 | Embryonic kidney cells |
| HepG2 | 7.8 | Liver cancer cells |
| A549 | 6.1 | Lung cancer cells |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.626G>A (p.Arg209His) | Missense | Rare | Likely loss of function; associated with nephronophthisis |
| c.1099C>T (p.Arg367*) | Nonsense | Rare | Premature stop; loss of function; Jeune syndrome |
| c.1873C>T (p.Arg625Trp) | Missense | Rare | Impaired IFT complex binding; ciliopathy |
Mutation functional classification
Loss of Function (LOF)
Most TTC21B mutations are loss-of-function, leading to truncated or unstable protein, disrupting retrograde IFT.
Gain of Function (GOF)
No evidence of gain-of-function mutations in TTC21B.
Dominant Negative (DN)
Not reported; disease inheritance is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • Cilium assembly | • Intraflagellar transport |
| • Protein transport | • Cell projection organization |
Pathways
• Intraflagellar transport (IFT)
• Ciliary signaling pathways
Protein Summary
The TTC21B protein (IFT139) is a 1319-amino acid component of the IFT-A complex, localized to the ciliary base and axoneme. It contains multiple TPR repeats that mediate protein-protein interactions essential for retrograde ciliary transport. Defects lead to impaired ciliary function and multisystem ciliopathies.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| TTC21B Knockout HEK293 Cell Line | EDJ-KQ2364 | Human | 79809 | Details Get a Quote |
| TTC21B Knockout A-549 Cell Line | EDJ-KQ24179 | Human | 79809 | Details Get a Quote |
| TTC21B Knockout HCT 116 Cell Line | EDJ-KQ24181 | Human | 79809 | Details Get a Quote |
| TTC21B Knockout HeLa Cell Line | EDJ-KQ24182 | Human | 79809 | Details Get a Quote |
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