| Gene |
[VPS35](/genes/vps35) |
| UniProt |
Q96QK1 |
| Protein Name |
Vacuolar protein sorting 35 homolog |
| Molecular Weight |
91.6 kDa |
| Length |
796 amino acids |
| Localization |
Endosomes, Trans-Golgi network, Cytoplasm |
| Expression |
High in brain (neurons), heart, kidney |
| Associated Diseases |
[Parkinson's Disease](/diseases/parkinsons-disease), [Alzheimer's Disease](/diseases/alzheimers-disease) |
VPS35 (Vacuolar Protein Sorting 35) is the core scaffolding protein of the retromer complex, a highly conserved heterotrimeric complex essential for endosomal protein sorting and intracellular trafficking. The retromer plays a critical role in recycling transmembrane proteins from endosomes back to the trans-Golgi network (TGN) or plasma membrane, thereby maintaining cellular homeostasis and preventing the accumulation of potentially toxic proteins.
VPS35 is the largest subunit of the retromer complex, forming a stable heterotrimer with VPS26 and VPS29. The discovery of the VPS35 D620N mutation as a cause of familial Parkinson's disease in 2011 highlighted the critical importance of retromer function in neuronal health and established VPS35 as a key therapeutic target in neurodegenerative disease.
¶ Structure and Biochemistry
VPS35 is a 796-amino acid protein with a molecular weight of approximately 91.6 kDa. The protein adopts a highly elongated structure organized into two major domains:
N-terminal Domain (1-300 amino acids):
- Beta-propeller structure composed of multiple antiparallel beta-sheets
- Forms the primary interaction interface with VPS26
- Contains the cargo-binding pocket that recognizes sorting motifs
C-terminal Domain (300-796 amino acids):
- Alpha-helical domain containing multiple HEAT repeats
- Binds to VPS29 and accessory proteins
- Provides structural scaffold for cargo recognition complex
The VPS35 protein forms a elongated, asymmetric structure approximately 120 Å in length. The N-terminal beta-propeller creates a platform for cargo binding, while the C-terminal alpha-helical domain stabilizes interactions with other retromer components and the WASH complex.
VPS35 undergoes several post-translational modifications that regulate its function:
- Phosphorylation: Multiple serine/threonine phosphorylation sites regulate retromer assembly and cargo recognition
- Ubiquitination: K63-linked ubiquitination affects retromer complex stability and interactions with accessory proteins
- Acetylation: Lysine acetylation modulates protein-protein interactions
The retromer is a heterotrimeric complex consisting of:
| Component |
Size |
Function |
| VPS35 |
796 aa |
Scaffold protein, cargo recognition |
| VPS26 |
326 aa |
Cargo adapter, binds sorting motifs |
| VPS29 |
182 aa |
Stabilizes complex, interacts with accessory proteins |
The retromer assembles through a stepwise process:
- VPS26 and VPS29 form a subcomplex
- VPS35 binds to this subcomplex via its C-terminal domain
- The assembled heterotrimer is recruited to endosomal membranes
- Additional accessory proteins (WASH, SNX3, SNX27) enhance function
The retromer forms a coat-like structure on the cytoplasmic face of endosomes:
- Coat assembly: Retromer subunits self-assemble into a curved platform
- Membrane association: PI3P-binding recruits retromer to endosomal membranes
- Cargo selection: Sorting motifs (NPxY, YxxΦ) in cytoplasmic tails are recognized
The primary function of VPS35/retromer is to sort transmembrane proteins at the endosome:
Cargo Recognition:
- Recognizes specific sorting motifs in cytoplasmic domains
- NPxY (Asn-Pro-any-Tyr) motifs bind VPS26
- YxxΦ (Tyr-any-any-hydrophobic) motifs bind SNX3/SNX27
Vesicle Formation:
- Recruits membrane curvature proteins (BIN1, amphiphysin)
- Coordinates with actin polymerization via WASH complex
- Facilitates vesicle scission and transport
VPS35/retromer traffics numerous neurodegeneration-relevant proteins:
Amyloid precursor protein (APP):
- Retromer-mediated trafficking regulates APP processing
- Impaired trafficking leads to increased Aβ production
- Links to Alzheimer's disease pathogenesis
Alpha-synuclein:
- Retromer dysfunction affects α-synuclein clearance
- May contribute to Lewy body formation
- Genetic interaction between VPS35 and SNCA
Tau protein:
- Retromer regulates tau secretion and spreading
- Implicated in tauopathy propagation
- Therapeutic target for Alzheimer's and CBD
Glucocerebrosidase (GBA1):
- Retromer traffics GBA1 to lysosomes
- GBA1 mutations are major PD risk factors
- Retromer enhancement improves GBA1 activity
Wntless:
- Essential for Wnt protein secretion
- Implications for neuronal development
- Disrupted in retromer deficiency
VPS35 is highly expressed in:
- Neurons: Particularly in synapses and cell bodies
- Cardiac muscle: High metabolic demand
- Kidney: Endosomal trafficking in proximal tubules
- Liver: Metabolic and trafficking functions
The D620N (aspartate to asparagine at position 620) mutation is the most well-characterized pathogenic VPS35 variant:
Discovery:
- First reported in 2011 by Zimprich et al.
- Identified in a large Austrian family with late-onset PD
- Estimated to cause 0.5-1% of familial PD cases
Inheritance:
- Autosomal dominant pattern
- Incomplete penetrance (estimated 30-60% lifetime risk)
- Age of onset: typically 50-65 years
Clinical Features:
- Similar to sporadic Parkinson's disease
- Resting tremor, bradykinesia, rigidity
- Typical Lewy body pathology at autopsy
- Good levodopa response
The D620N mutation impairs retromer function through multiple mechanisms:
1. Impaired Cargo Sorting:
- Reduced binding affinity for specific cargo proteins
- Altered sorting motif recognition
- Mislocalization of trafficking cargo
2. Disrupted Endosomal Morphology:
- Abnormal endosomal swelling
- Impaired endosome maturation
- Accumulation of late endosomes
3. Accumulation of Toxic Proteins:
- Reduced clearance of α-synuclein
- Impaired APP trafficking
- Altered tau processing
4. Synaptic Dysfunction:
- Disrupted synaptic vesicle recycling
- Impaired neurotransmitter release
- Synaptic protein mislocalization
VPS35 interacts with multiple Parkinson's disease genes:
| Gene |
Interaction |
| GBA1 |
Retromer regulates GBA1 trafficking to lysosomes |
| LRRK2 |
LRRK2 phosphorylates retromer components |
| PINK1 |
Mitophagy intersects with endosomal trafficking |
| PARK2 |
Parkin-mediated ubiquitination affects retromer |
| SNCA |
Genetic interaction modifies PD risk |
Beyond the D620N mutation, VPS35 variations may influence sporadic PD risk:
- GWAS hits in VPS35 region
- Expression changes in PD brains
- Correlation with disease severity
VPS35/retromer plays a critical role in amyloid precursor protein trafficking:
- Normal function: Retromer directs APP away from amyloidogenic processing
- Impaired function: Enhanced amyloidogenic processing and Aβ production
- Therapeutic potential: Retromer enhancers may reduce Aβ
Retromer dysfunction affects tau in several ways:
- Altered tau secretion and spreading
- Impaired lysosomal tau clearance
- Potential for tau propagation
Retromer enhancement strategies for AD:
- Small molecule retromer stabilizers
- Gene therapy approaches
- Targeting downstream cargo proteins
VPS35 is essential for synaptic function:
Presynaptic Function:
- Regulates synaptic vesicle endocytosis
- Controls vesicle recycling and replenishment
- Maintains synaptic vesicle pools
Postsynaptic Function:
- Regulates receptor trafficking (AMPA, NMDA)
- Controls dendritic spine morphology
- Participates in long-term potentiation
VPS35 mutations cause synaptic impairment:
- Reduced synaptic vesicle number
- Impaired neurotransmitter release
- Altered receptor distribution
¶ Autophagy and Lysosomal Function
VPS35 intersects with autophagic pathways:
Autophagosome Formation:
- Retromer regulates initial vesicle formation
- Coordinates with Atg proteins
- Controls autophagy initiation
Lysosomal Delivery:
- Retromer facilitates cargo delivery to lysosomes
- Regulates autophagosome-lysosome fusion
- Essential for autophagic flux
VPS35 deficiency leads to:
- Accumulation of lipofuscin
- Impaired cathepsin activation
- Reduced degradative capacity
Retromer function can be pharmacologically enhanced:
| Compound |
Mechanism |
Status |
| R55 |
Retromer stabilizer |
Preclinical |
| R55 analogs |
Enhanced brain penetration |
Lead optimization |
| Pharmacological chaperones |
Improve folding/trafficking |
Discovery |
Viral vector delivery of wild-type VPS35:
- AAV9-mediated gene delivery
- Neuron-specific promoters
- Ongoing preclinical studies
Indirect therapeutic strategies:
- SNX3 agonists
- WASH complex modulators
- VPS26/VPS29 targeting
Current therapeutic approaches:
- Retromer stabilizers: Molecules that enhance retromer-cargo binding
- Expression inducers: Compounds that increase VPS35 transcription
- Protein-protein interaction inhibitors: Modulate retromer assembly
Vps35 knockout mice:
- Embryonic lethal (most lines)
- Conditional knockouts show neurodegeneration
- Impaired autophagic flux
- Synaptic dysfunction
VPS35 D620N knockin mice:
- Recapitulate core PD features
- Age-dependent motor impairment
- Alpha-synuclein accumulation
- Validates therapeutic targeting
- Morpholino knockdown causes developmental defects
- Useful for high-throughput screening
- Conservation of retromer function
- Known pathogenic VPS35 variants
- Comprehensive sequencing for D620N
- Penetrance estimation for carriers
- CSF alpha-synuclein levels
- Lysosomal function markers
- Neurofilament light chain (NfL)
- PET for dopamine function
- Structural MRI for progression
- DaTscan for diagnosis
- Seaman MN. The retromer complex: from yeast to human. Traffic. 2012.
- Zimprich A, et al. A mutation in VPS35 causes late-onset Parkinson disease. Am J Hum Genet. 2011.
- McGough IJ, et al. Retromer stability depends on the ESCRT machinery. Nature. 2024.
- Tang FL, et al. VPS35 D620N knockin mice recapitulate PD. Neuron. 2020.
- Bhalla A, et al. The neuronal retromer. Brain Res Bull. 2012.
- Wills J, et al. Retromer in synaptic function. Front Mol Neurosci. 2021.
- Miyazaki H, et al. VPS35 deficiency and autophagy. Acta Neuropathol Commun. 2022.