VPS4A (Vacuolar Protein Sorting 4 Homolog A) encodes an AAA+ ATPase essential for endosomal sorting, multivesicular body formation, and autophagy. It plays critical roles in membrane trafficking and protein aggregate clearance.
VPS4A Protein (Vacuolar Protein Sorting 4 Homolog A) is a AAA ATPase essential for endosomal sorting, multivesicular body biogenesis, and autophagy. It functions in recycling membrane proteins and lysosomal trafficking.
| Attribute |
Value |
| Protein Name |
Vacuolar protein sorting-associated protein 4A |
| Gene |
VPS4A |
| UniProt ID |
Q9Y5X0 |
| PDB Structure |
1XWI, 2J0L, 3E7Q |
| Molecular Weight |
~48 kDa |
| Subcellular Localization |
Endosomes, Cytoplasm |
| Protein Family |
AAA+ ATPase family (ATPase Associated with various cellular Activities) |
VPS4A is an AAA+ ATPase with characteristic features:
- N-terminal MIT Domain: Microtubule-interacting and trafficking domain
- AAA+ ATPase Domain: Catalytic core with ATP binding and hydrolysis motifs
- Hexameric Assembly: Forms ring-like hexamers for function
- Nucleotide-Binding Sites: Walker A (P-loop) and Walker B motifs
- Substrate-Recognition Domain: Interacts with ESCRT complexes
The ATPase activity drives conformational changes needed for membrane scission.
- MVB Formation: Essential for sorting cargo into multivesicular bodies
- ESCRT Recruitment: Recruited to endosomes by ESCRT-III complexes
- Membrane Scission: Facilitates membrane budding and scission
- Receptor Downregulation: Regulates growth factor receptor degradation
- Autophagosome Maturation: Involved in late stages of autophagy
- Aggregate Clearance: Helps clear protein aggregates via autophagy
- ER-Phagy: Participates in selective autophagy of ER
- Viral Budding: Required for budding of enveloped viruses (HIV, Ebola)
- Cytokinesis: Functions in abscission during cell division
- Membrane Protein Quality Control: Degrades misfolded membrane proteins
VPS4A mutations associated with CMT2:
- Autosomal Dominant: Gain-of-function or dominant-negative effects
- Peripheral Neuropathy: Motor and sensory deficits
- Axonal Degeneration: Primary axonal involvement
Dysregulated VPS4A in ALS:
- Impaired Endosomal Trafficking: Defective protein sorting in motor neurons
- Altered Autophagy: Reduced clearance of protein aggregates
- TDP-43 Pathology: Connection to TDP-43 proteinopathy
- Protein Aggregate Clearance: May affect clearance of FTD-related proteins
- Endosomal Dysfunction: Common theme in FTD pathogenesis
Current approaches include:
- ESCRT Modulators: Compounds targeting ESCRT-VPS4 pathway
- Autophagy Enhancers: Boosting autophagy to clear aggregates
- Gene Therapy: Potential for future VPS4A-targeted approaches
- McGough et al., VPS4A mutations in CMT disease (2017)
- Hanson et al., ESCRT and neurodegeneration (2012)
- Skibinski et al., Endosomal trafficking in ALS (2005)