The UBA1 gene (Ubiquitin-Like Modifier Activating Enzyme 1) encodes the primary E1 ubiquitin-activating enzyme in human cells, initiating the ubiquitin-proteasome system (UPS) cascade essential for protein degradation and cellular proteostasis. Dysfunction of UBA1 has been implicated in neurodegeneration, spinal muscular atrophy, and the recently described VEXAS syndrome.
The UBA1 gene is located on chromosome Xp11.3 and encodes the principal E1 ubiquitin-activating enzyme in mammalian cells[1]. UBA1 catalyzes the first step of the ubiquitination cascade — ATP-dependent activation of ubiquitin, forming a thioester bond between UBA1's catalytic cysteine and ubiquitin's C-terminal glycine[2]. As the apex enzyme of the ubiquitin-proteasome system (UPS), UBA1 is essential for virtually all ubiquitin-dependent processes in the cell, including protein degradation, DNA repair, cell cycle regulation, and signal transduction[3]. [1]
| | | [2]
|---|---| [3]
| Gene Symbol | UBA1 | [4]
| Full Name | Ubiquitin-Like Modifier Activating Enzyme 1 |
| Aliases | UBE1, A1S9T, POC20 |
| Chromosomal Location | Xp11.3 |
| NCBI Gene ID | 7317 |
| OMIM | 314370 |
| Ensembl | ENSG00000130985 |
| UniProt | P22314 |
| Associated Diseases | VEXAS syndrome, X-linked SMA, neurodegeneration |
UBA1 catalyzes the first committed step of ubiquitination[1]:
As the upstream activating enzyme, UBA1 is required for[2]:
UBA1 is expressed as two isoforms from alternative translation initiation[3]:
VEXAS (Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic) syndrome is caused by somatic mutations in UBA1[4]:
Infantile X-linked SMA with arthrogryposis is associated with UBA1 loss-of-function[5]:
UBA1 function is broadly relevant to neurodegeneration[6]:
| Variant | Effect | Clinical Significance |
|---|---|---|
| M41T | Loss of UBA1b isoform | VEXAS syndrome (somatic) |
| M41V | Loss of UBA1b isoform | VEXAS syndrome (somatic) |
| M41L | Loss of UBA1b isoform | VEXAS syndrome (somatic) |
| Splice site mutations | Variable loss of function | X-linked infantile SMA |
| S56P/G | Missense, reduced activity | X-linked SMA-like phenotype |
UBA1 is ubiquitously expressed, essential in all cell types[1]:
Expression is highest in metabolically active, post-mitotic cells with high protein turnover demands.
Hershko A & Ciechanover A, The ubiquitin system (1998). 1998. ↩︎
Beck DB et al. Somatic mutations in UBA1 and severe adult-onset autoinflammatory disease (2020). 2020. ↩︎
Ramser J et al. Rare missense and synonymous variants in UBE1 are associated with X-linked infantile spinal muscular atrophy (2008). 2008. ↩︎
Thibaudeau TA & Smith DM, A practical review of proteasome pharmacology (2019). 2019. ↩︎