TTPA Gene: Alpha-Tocopherol Transfer Protein
Key regulator of vitamin E homeostasis and genetic basis of ataxia with vitamin E deficiency (AVED)
Gene Information Card
| Symbol | TTPA |
|---|---|
| Full Name | Alpha-tocopherol transfer protein |
| Gene Type | Protein coding |
| Chromosomal Location | 8q13.1 |
| NCBI Gene ID | 7274 ncbi.nlm.nih.gov/gene/7274 |
| Ensembl ID | ENSG00000137561 |
| UniProt ID | P49638 |
| OMIM ID | 600415 |
| HGNC ID | 12404 |
| Aliases | AVED, TTP1, alphaTTP |
Description
The TTPA gene encodes the alpha-tocopherol transfer protein (α-TTP), a cytosolic protein that specifically binds alpha-tocopherol (the most biologically active form of vitamin E) and facilitates its incorporation into lipoproteins for hepatic secretion and systemic distribution. Loss-of-function mutations in TTPA cause ataxia with vitamin E deficiency (AVED), a neurodegenerative disorder characterized by impaired vitamin E transport and subsequent oxidative stress.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Ataxia with vitamin E deficiency (AVED) | Loss-of-function mutations in TTPA impair hepatic secretion of alpha-tocopherol, leading to severe vitamin E deficiency and progressive neurodegeneration. | ClinVar, OMIM |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 28.7 | High |
| Brain | 3.2 | Low |
| Placenta | 2.1 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 | 15.4 | Hepatocellular carcinoma; high expression |
| SH-SY5Y | 1.8 | Neuroblastoma; low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.744delA | Frameshift deletion | Common in North African AVED patients | Loss of function; truncated protein |
| c.513_514insTT | Frameshift insertion | Reported in AVED families | Loss of function; premature stop codon |
| c.400C>T (p.Arg134* ) | Nonsense | Rare | Loss of function; nonsense-mediated decay |
Mutation functional classification
Loss of Function (LOF)
Most TTPA mutations are loss-of-function, leading to reduced or absent alpha-tocopherol transfer activity and causing AVED.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations reported; AVED is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • vitamin E binding (GO:0008431) | • lipid transporter activity (GO:0005319) |
| • sterol transporter activity (GO:0015248) | • sterol transport (GO:0015918) |
| • cholesterol transport (GO:0030301) | • response to drug (GO:0042493) |
Pathways
• Vitamin E metabolism and transport
• Lipoprotein metabolism
Protein Summary
Alpha-tocopherol transfer protein (α-TTP) is a 278-amino acid cytosolic protein predominantly expressed in the liver. It specifically binds alpha-tocopherol and mediates its transfer from the endosomal compartment to the plasma membrane for incorporation into VLDL. This process is essential for maintaining plasma vitamin E levels and protecting tissues from oxidative damage. Mutations in TTPA disrupt this transport, leading to vitamin E deficiency and progressive neurodegeneration.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| TTPA Knockout HEK293 Cell Line | EDJ-KQ5979 | Human | 7274 | Details Get a Quote |
| TTPAL Knockout HEK293 Cell Line | EDJ-KQ15982 | Human | 79183 | Details Get a Quote |
| TTPAL Knockout A-549 Cell Line | EDJ-KQ47028 | Human | 79183 | Details Get a Quote |
| TTPAL Knockout HCT 116 Cell Line | EDJ-KQ47029 | Human | 79183 | Details Get a Quote |
| TTPA Knockout HCT 116 Cell Line | EDJ-KQ29555 | Human | 7274 | Details Get a Quote |
| TTPAL Knockout HeLa Cell Line | EDJ-KQ45809 | Human | 79183 | Details Get a Quote |
| TTPA Knockout HeLa Cell Line | EDJ-KQ54703 | Human | 7274 | Details Get a Quote |
| TTPA Knockout A-549 Cell Line | EDJ-KQ63191 | Human | 7274 | Details Get a Quote |
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