| ATP13A3 |
|---|
| Gene Symbol | ATP13A3 |
| Full Name | ATPase Cation Transporting 13A3 (P5-ATPase) |
| Chromosome | 3q29 |
| NCBI Gene ID | 79572 |
| OMIM | 615044 |
| Ensembl ID | ENSG00000165621 |
| UniProt ID | Q9HAW4 |
| Protein Length | 1058 amino acids |
| Associated Diseases | Parkinson's Disease, Pulmonary Hypertension |
ATP13A3 (ATPase Cation Transporting 13A3) encodes a P5-type P-type ATPase (P5-ATPase) that functions as a cation transporter with specificity for calcium and other divalent cations. Located on chromosome 3q29, this protein is closely related to ATP13A2 (PARK9), which is linked to Kufor-Rakeb syndrome and early-onset Parkinson's disease. ATP13A3 plays critical roles in cellular calcium homeostasis, lysosomal function, and autophagy regulation, all of which are pathways central to neurodegenerative disease pathogenesis.
P5-ATPases represent an ancient and poorly characterized subfamily of P-type ATPases that transport cations across cellular membranes. While ATP13A2 has been extensively studied in the context of neurodegeneration, ATP13A3 has emerged as an important modifier of Parkinson's disease risk and is implicated in pulmonary vascular disease.
¶ Gene Structure and Evolution
The ATP13A3 gene is located on chromosome 3q29 and consists of 25 exons spanning approximately 25 kb of genomic DNA. The gene encodes a protein of 1058 amino acids with a molecular weight of approximately 120 kDa. The promoter region contains response elements for various cellular stress signals and nutritional status.
¶ Protein Domain Architecture
P5-ATPases share the characteristic architecture of P-type ATPases:
| Domain |
Function |
| A-domain (actuator) |
ATPase activity, phosphorylation |
| P-domain (phosphorylation) |
ATP binding and hydrolysis |
| N-domain (nucleotide-binding) |
Energy transduction |
| M-domain (transmembrane) |
Ion transport channel |
ATP13A3 is conserved across vertebrates:
- Human ATP13A3: 1058 amino acids
- Mouse Atp13a3: 94% amino acid identity
- Zebrafish atp13a3: 72% identity
- Drosophila: ortholog present
The P5-ATPase subfamily diverged early in evolution, with distinct expansion in vertebrates.
ATP13A3 functions as an active cation transporter:
Substrate Specificity:
- Calcium (Ca²⁺) — primary substrate
- Manganese (Mn²⁺) — secondary substrate
- Other divalent cations possible
Transport Mechanism:
- Active transport requiring ATP hydrolysis
- Electrogenic (transports positive charge)
- Coupled to proton counter-transport
Ion Gradient Maintenance:
- Maintains cytosolic calcium levels
- Contributes to lysosomal calcium stores
- Regulates endoplasmic reticulum calcium
ATP13A3 localizes to multiple cellular compartments:
Primary Localization:
- Endoplasmic reticulum (ER)
- Lysosomal membranes
- Endosomal compartments
Dynamic Relocalization:
- Can translocate to plasma membrane
- Responds to cellular stress
- Alters with disease states
ATP13A3 and ATP13A2 (PARK9) are closely related:
Functional Overlap:
- Both are P5-ATPases
- Similar substrate specificity
- Compensatory functions possible
Differences:
- Different tissue expression patterns
- Distinct subcellular localization
- Non-redundant in some contexts
Interaction:
- May form heterooligomers
- Potential functional synergy
- Shared disease mechanisms
ATP13A3 shows wide expression:
High Expression:
- Brain (substantia nigra, hippocampus, cortex)
- Lung (especially pulmonary vasculature)
- Heart
- Testis
Moderate Expression:
- Liver, kidney
- Skeletal muscle
- Pancreas
In the brain, ATP13A3 is expressed in:
Substantia Nigra:
- High expression in dopaminergic neurons
- Lower in other brain regions
- Cell-type specific expression
Other Regions:
- Hippocampus (CA1-CA3, dentate gyrus)
- Cerebral cortex (layers V-VI)
- Cerebellum (Purkinje cells)
- Striatum
- Neurons (primary expression)
- Astrocytes (lower)
- Microglia (minimal)
- Endothelial cells (lung, brain)
ATP13A3 variants are associated with Parkinson's disease risk:
Genetic Evidence:
- Rare missense variants increase PD risk
- R474Q and A889T identified as risk variants
- Independent replication in multiple cohorts
- Likely effect through loss of function
Pathogenic Mechanisms:
-
Lysosomal Dysfunction:
- Impaired lysosomal calcium handling
- Reduced lysosomal acidification
- Dysregulated autophagy
-
Alpha-Synuclein Clearance:
- Impaired autophagic degradation of alpha-synuclein
- Accumulation of toxic aggregates
- Enhanced spread of pathology
-
ER Stress:
-
Mitochondrial Dysfunction:
- Altered calcium handling
- Impaired mitochondrial quality control
- Enhanced oxidative stress
Clinical Features:
- Typical idiopathic PD phenotype
- Variable age of onset
- Similar progression to sporadic PD
- May have slightly earlier onset
ATP13A3 is implicated in pulmonary arterial hypertension (PAH):
Genetic Evidence:
- Dominant mutations cause familial PAH
- De novo variants in sporadic cases
- Reduced penetrance
Pathogenic Mechanisms:
-
Vascular Smooth Muscle Proliferation:
- Enhanced proliferation
- Reduced apoptosis
- Intimal hyperplasia
-
Endothelial Dysfunction:
- Impaired vasodilation
- Enhanced inflammation
- Pro-thrombotic state
Clinical Features:
- Mean pulmonary artery pressure >20 mmHg
- Pulmonary vascular resistance increase
- Right heart failure progression
Cancer:
- Altered expression in some cancers
- Potential role in cell proliferation
- May affect tumor progression
Other Neurodegenerative Diseases:
ATP13A3 loss of function leads to lysosomal impairment:
Calcium Handling:
- Reduced lysosomal calcium uptake
- Dysregulated lysosomal pH
- Impaired calcium signaling
Autophagy Impairment:
- Reduced autophagosome formation
- Impaired autophagosome-lysosome fusion
- Accumulation of undigested material
Consequences:
- Alpha-synuclein accumulation
- Mitochondrial dysfunction
- Cellular stress
ATP13A3 is critical for cellular calcium balance:
Cytosolic Calcium:
- Contributes to calcium extrusion
- Protects against calcium overload
- Modulates calcium signaling
Organellar Calcium:
- ER calcium refilling
- Lysosomal calcium storage
- Mitochondrial calcium handling
ATP13A3 dysfunction triggers ER stress:
Unfolded Protein Response:
- PERK pathway activation
- IRE1 pathway engagement
- ATF6 cleavage
Cellular Consequences:
- Pro-apoptotic signaling
- Reduced protein synthesis
- Enhanced cellular vulnerability
Small Molecule Modulators:
- ATP13A3 activity enhancers
- Lysosomal function modulators
- Calcium homeostasis agents
Gene Therapy Approaches:
- AAV-mediated ATP13A3 delivery
- CRISPR-based gene editing
- RNA-based therapeutics
Lysosomal Enhancement:
- Autophagy inducers
- Lysosomal acidification enhancers
- mTOR inhibitors
Calcium Stabilization:
- Calcium channel modulators
- Calcium buffering agents
Neuroprotective Strategies:
- Antioxidants
- Mitochondrial protectants
- ER stress inhibitors
| Application |
Target |
Vendor |
| WB |
ATP13A3 |
Abcam, Sigma |
| IHC |
ATP13A3 |
Santa Cruz |
| IP |
ATP13A3 |
Bethyl Labs |
| Flow cytometry |
ATP13A3 |
BioLegend |
- SH-SY5Y (dopaminergic)
- HEK293T (overexpression)
- Primary neurons (mouse/rat)
- Fibroblasts (patient-derived)
- pcDNA3.1-ATP13A3
- pLenti-CRISPR ATP13A3 knockout
- ATP13A3-GFP fusion
- ATP13A3-Myc constructs
Atp13a3 knockout:
- Partial embryonic lethality
- Growth retardation
- Neurological deficits
- Impaired motor function
- Human ATP13A3 wild-type expression
- PD-associated mutant expression
- Conditional knockout systems
- Alpha-synuclein overexpression with ATP13A3 loss
- MPTP/6-OHDA models with ATP13A3 modulation
- ATP13A3 expression as PD biomarker
- Variant screening for risk assessment
- Therapeutic response monitoring
- Genetic testing for ATP13A3 variants
- Functional assays for variant pathogenicity
- Combination with other PD genes
- Rare missense variants in PD
- Loss-of-function variants in PAH
- No common pathogenic variants
- Founder mutations in specific populations
- Variant frequencies vary by ancestry
- Most studies in European populations
- Need for diverse cohort studies
¶ Clinical Features and Diagnosis
ATP13A3-related PD shows typical idiopathic features:
Motor Symptoms:
- Resting tremor (4-6 Hz)
- Bradykinesia
- Rigidity
- Postural instability
- Gait freezing
Non-Motor Symptoms:
- REM sleep behavior disorder
- Olfactory dysfunction
- Constipation
- Depression/anxiety
- Cognitive impairment (later)
Disease Progression:
- Hoehn & Yahr stages 1-5
- Motor fluctuations with levodopa
- Dyskinesias with long-term treatment
- Similar progression to sporadic PD
Age of Onset:
- Variable (45-75 years)
- Often earlier than typical PD
- Some cases with early onset (<50 years)
ATP13A3-related PAH has characteristic features:
Clinical Presentation:
- Progressive dyspnea
- Fatigue
- Syncope on exertion
- Chest pain
- Edema
Hemodynamic Findings:
- Mean pulmonary artery pressure >20 mmHg
- Pulmonary vascular resistance >2 Wood units
- Normal pulmonary capillary wedge pressure
- Reduced cardiac output
Disease Course:
- Progressive right heart failure
- Poor prognosis without treatment
- May be isolated or associated with other conditions
For PD:
- Clinical diagnosis using UK Brain Bank criteria
- DaT-SPECT imaging for dopamine transporter loss
- Genetic testing for ATP13A3 variants
- Exclusion of secondary causes
For PAH:
- Right heart catheterization
- Chest CT scan
- Pulmonary function tests
- Genetic testing for ATP13A3
¶ P5-ATPase Structure and Function
ATP13A3 belongs to the P-type ATPase family:
Catalytic Cycle:
- ATP binding to N-domain
- Phosphorylation of P-domain aspartate
- Conformational change (E1 to E2)
- Ion transport across membrane
- Dephosphorylation and return to E1
Ion Binding Site:
- Conserved aspartate residues
- Coordinated by transmembrane helices
- Selectivity filter determines specificity
Energy Coupling:
- ATP hydrolysis drives transport
- Conformational changes couple energy
- Similar to other P-type ATPases
¶ Lysosomal Calcium Handling
ATP13A3 is critical for lysosomal calcium:
Calcium Storage:
- Lysosomes store calcium for signaling
- ATP13A3 pumps calcium into lysosomes
- Maintains calcium gradient
Calcium Release:
- Lysosomal calcium release via channels
- Triggers autophagy initiation
- Activates calmodulin and downstream effectors
Dysfunctional Consequences:
- Impaired calcium signaling
- Reduced autophagy
- Alpha-synuclein accumulation
ATP13A3 modulates autophagy through:
Autophagosome Formation:
- Calcium signaling promotes nucleation
- PI3K complex recruitment
- LC3 lipidation
Lysosomal Fusion:
- SNARE complex assembly
- V-ATPase acidification
- Calcium gradient maintenance
Degradation:
- Hydrolase activation
- Autophagic flux monitoring
- Defective autophagy with ATP13A3 loss
ATP13A3 dysfunction triggers ER stress:
PERK Pathway:
- eIF2α phosphorylation
- ATF4 translation
- CHOP expression
IRE1 Pathway:
- XBP1 splicing
- CHOP induction
- Apoptotic signaling
ATF6 Pathway:
- ATF6 cleavage
- ER chaperone upregulation
- Unfolded protein response
ATP13A3 affects mitochondrial function:
Mitochondrial Calcium:
- Mitochondrial calcium uptake
- Metabolic regulation
- Apoptosis control
Quality Control:
- Mitophagy regulation
- Mitochondrial dynamics
- Bioenergetic function
Consequences of Dysfunction:
- Reduced ATP production
- Enhanced ROS generation
- Apoptotic vulnerability
¶ Management and Treatment
Pharmacological:
- Levodopa/carbidopa
- Dopamine agonists (pramipexole, ropinirole)
- MAO-B inhibitors (selegiline, rasagiline)
- COMT inhibitors (entacapone)
Surgical:
- Deep brain stimulation (STN or GPi)
- Levodopa-carbidopa intestinal gel
Supportive:
- Physical therapy
- Occupational therapy
- Speech therapy
Targeted Therapies:
- Endothelin receptor antagonists (bosentan, ambrisentan)
- PDE5 inhibitors (sildenafil, tadalafil)
- Soluble guanylate cyclase stimulators
- Prostacyclin analogs
Supportive:
- Anticoagulation
- Diuretics
- Oxygen therapy
Advanced:
- Lung transplantation
- Atrial septostomy
¶ Research and Clinical Trials
- ATP13A3 variant screening in PD cohorts
- Functional validation of variants
- Biomarker development
- Drug target validation
Direct Targets:
- ATP13A3 expression enhancers
- Lysosomal function modulators
- Calcium homeostasis agents
Indirect Strategies:
- Autophagy inducers
- ER stress inhibitors
- Neuroprotective agents
- Patient-derived fibroblasts
- Induced neurons (iPSC)
- Animal models with ATP13A3 manipulation
- Organoid systems
graph TD
A["ATP13A3"] --> B["ATP13A2"]
A --> C["LAMP2"]
A --> D["V-ATPase"]
A --> E["Calmodulin"]
B --> F["Alpha-synuclein"]
C --> G["Autophagy"]
D --> H["Lysosome"]
E --> I["Calcium Signaling"]
- ATP13A2 (PARK9) — closest homolog
- ATP13A4 — another family member
- V-ATPase — lysosomal acidification
- LAMP2 — lysosomal membrane
¶ Outstanding Questions
- What is the exact substrate specificity of ATP13A3?
- How do ATP13A3 variants cause selective vulnerability?
- Can ATP13A3 function be restored therapeutically?
- What determines tissue-specific effects (brain vs. lung)?
- Cryo-EM structure determination
- Substrate transport mechanism
- Tissue-specific knockout models
- Therapeutic compound screening