TMEM138: Transmembrane Protein 138
A ciliary protein associated with Joubert syndrome and related ciliopathies
Gene Information Card
| Symbol | TMEM138 |
|---|---|
| Full Name | Transmembrane Protein 138 |
| Gene Type | Protein coding |
| Chromosomal Location | 11q21 |
| NCBI Gene ID | 51524 ncbi.nlm.nih.gov/gene/51524 |
| Ensembl ID | ENSG00000149489 |
| UniProt ID | Q9NYS0 |
| OMIM ID | 614459 |
| HGNC ID | 26944 |
| Aliases | HSPC196, MGC13016 |
Description
TMEM138 encodes a transmembrane protein localized to the ciliary transition zone, essential for ciliogenesis and ciliary signaling. Mutations in this gene disrupt ciliary function and are associated with Joubert syndrome, a neurodevelopmental ciliopathy characterized by cerebellar vermis hypoplasia, intellectual disability, and retinal dystrophy.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Joubert syndrome 16 | Loss-of-function mutations impair ciliary transition zone assembly, leading to defective ciliary signaling and neurodevelopmental abnormalities. | OMIM #614465; ClinVar pathogenic variants |
| Joubert syndrome-related disorders | Disruption of TMEM138 function contributes to ciliopathy phenotypes including retinal degeneration and renal cysts. | OMIM #614459; literature review |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 12.3 | Medium |
| Cerebellum | 8.7 | Low |
| Kidney | 6.5 | Low |
| Retina | 5.9 | Low |
| Brain cortex | 4.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK 293 | 15.2 | Moderate expression |
| HeLa | 10.1 | Moderate expression |
| SH-SY5Y | 7.3 | Low expression |
| ARPE-19 | 6.8 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.529C>T (p.Arg177*) | Nonsense | Rare | Loss of function; truncation of protein |
| c.344G>A (p.Arg115Gln) | Missense | Rare | Likely pathogenic; disrupts protein stability |
| c.1A>G (p.Met1?) | Start loss | Rare | Loss of function; no protein translation |
Mutation functional classification
Loss of Function (LOF)
Most TMEM138 mutations are loss-of-function, leading to truncated or unstable protein, impairing ciliary transition zone integrity.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations reported.
View complete mutation data：
Gene Ontology (GO)
| • protein binding (GO:0005515) | • integral component of membrane (GO:0016021) |
| • cell projection organization (GO:0030030) | • cilium assembly (GO:0060271) |
| • cilium (GO:0005929) |
Pathways
• Ciliopathy pathway (KEGG)
• Ciliary transition zone assembly
Protein Summary
TMEM138 is a 338-amino-acid transmembrane protein with four predicted transmembrane domains. It localizes to the ciliary transition zone and interacts with other ciliopathy-associated proteins such as TMEM216 and TMEM237. The protein is essential for proper ciliary membrane composition and signaling, particularly in the brain, retina, and kidney.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| TMEM138 Knockout HEK293 Cell Line | EDJ-KQ11127 | Human | 51524 | Details Get a Quote |
| TMEM138 Knockout A-549 Cell Line | EDJ-KQ39110 | Human | 51524 | Details Get a Quote |
| TMEM138 Knockout HeLa Cell Line | EDJ-KQ39112 | Human | 51524 | Details Get a Quote |
| TMEM138 Knockout HCT 116 Cell Line | EDJ-KQ37799 | Human | 51524 | Details Get a Quote |
