TOR1A (Torsin-1A) is a AAA+ ATPase protein located primarily in the endoplasmic reticulum and nuclear envelope. It is encoded by the TOR1A gene and is essential for nuclear envelope and ER organization. Mutations in TOR1A cause early-onset generalized dystonia (DYT1). [1]
| Torsin-1A Protein | |
|---|---|
| Protein Name | Torsin-1A (TOR1A) |
| Gene | [TOR1A](/genes/tor1a) |
| UniProt ID | [Q9UHB6](https://www.uniprot.org/uniprot/Q9UHB6) |
| PDB Structures | 5J1V, 5J1X, 4TUW |
| Molecular Weight | 38 kDa |
| Subcellular Localization | Endoplasmic Reticulum, Nuclear Envelope |
| Protein Family | AAA+ ATPase family |
TOR1A is a 332-amino acid protein belonging to the AAA+ (ATPases Associated with diverse cellular Activities) family. The protein contains: [2]
The AAA+ domain adopts a characteristic Rossmann-like fold with Walker A (P-loop) and Walker B motifs essential for ATP binding and hydrolysis. The protein forms hexameric ring structures that exert force on substrates.
TOR1A participates in nuclear envelope reformation during mitosis and helps maintain nuclear envelope integrity. It localizes to the inner nuclear membrane and interacts with nuclear pore complex proteins including NUP153 and NUP98. [3]
The protein facilitates the removal of mislocalized inner nuclear membrane proteins and helps reshape the envelope during nuclear envelope breakdown and reassembly in cell division.
The protein is involved in ER quality control processes, including the degradation of misfolded proteins through the ERAD pathway. TOR1A interacts with SEL1L and OS-9, key components of the ERAD machinery.
TOR1A has been implicated in lipid droplet formation and distribution, suggesting roles in cellular energy homeostasis. It localizes to lipid droplet surfaces and may regulate lipase access to stored triglycerides.
| Partner Protein | Interaction Type | Functional Consequence |
|---|---|---|
| LAP1 (Lamina-associated polypeptide 1) | Direct binding | NE organization |
| MAN1 (MAN1 domain containing 1) | Direct binding | Nuclear envelope integrity |
| NUP153 | Direct binding | Nuclear pore function |
| YB-1 (YBX1) | Direct binding | mRNA export regulation |
The most well-established link between TOR1A and disease is autosomal dominant early-onset generalized dystonia (DYT1). The most common mutation is a deletion of a glutamic acid (E302/303, also written as ΔE302/303) in the protein, which disrupts its ATPase activity and leads to abnormal protein aggregation. [4]
Mechanism of DYT1 dystonia:
Some studies have suggested potential connections between TOR1A variants and PD risk, though the evidence is less conclusive. The protein's role in ER stress response may be relevant to alpha-synuclein toxicity. [5]
Potential PD connections:
Studies in DYT1 carriers have revealed: [6]
Several animal models have been developed to study DYT1 dystonia: [7]
Ozelius LJ et al. The TOR1A (DYT1) gene product: A target for dystonia therapy. Neurotherapeutics. 2020. ↩︎
Nery FC et al. TorsinA and the nuclear envelope. Advances in Neurobiology. 2023. ↩︎
Gonzalez-Alegre P. Molecular pathways involved in neurodegeneration in DYT1 dystonia. Journal of Neurology Sciences. 2019. ↩︎
Kawarai T et al. Motor cortex hyperexcitability in DYT1 dystonia. Parkinsonism Relat Disord. 2016. ↩︎
Hettich J et al. TorsinA and the unfolded protein response. Cell Death Discovery. 2020. ↩︎
Niccolini F et al. Dystonia in DYT1 knock-in mice: a PET study. J Neurol Neurosurg Psychiatry. 2015. ↩︎
Ledoux MS et al. Animal models of DYT1 dystonia. Neurobiology of Disease. 2019. ↩︎