| 2025 |
Cryo-EM structures of human monomeric ATP9A at 2.2 Å resolution in the outward-facing E2P state revealed a unique gating mechanism: unlike canonical P-type ATPases where gating is driven by TM1/TM2 helix movement linked to the A domain, ATP9A outward gating is achieved by movement of TM6-10 helices, likely initiated by TM6 unwinding, creating a larger phospholipid binding cavity. ATP9A does not require the auxiliary subunit CDC50 protein. ATPase activity is significantly increased by negatively charged phospholipids (phosphatidylserine, phosphatidylinositol, and phosphorylated PI species) but not electroneutral phospholipids. Molecular simulations showed spontaneous binding of phosphorylated PI species in the translocation pathway. |
Cryo-EM structure determination, ATPase activity assay, molecular dynamics simulation |
The Journal of biological chemistry |
High |
40876594
|
| 2016 |
ATP9A localizes to phosphatidylserine (PS)-positive early and recycling endosomes (but not late endosomes) in HeLa cells. Depletion of ATP9A delayed recycling of transferrin from endosomes to the plasma membrane and caused accumulation of glucose transporter 1 (GLUT1) in endosomes. ATP9A depletion did not affect early/late endosomal transport and degradation of EGF, nor transport of Shiga toxin B from early/recycling endosomes to the Golgi. |
siRNA knockdown, fluorescence microscopy/subcellular fractionation, transferrin recycling assay, GLUT1 localization assay |
Molecular biology of the cell |
High |
27733620
|
| 2018 |
ATP9A is part of an evolutionarily conserved endosome-associated membrane remodelling complex composed of MON2, DOPEY2, and ATP9A (putative aminophospholipid translocase). This complex associates with SNX3-retromer to mediate endosome-to-Golgi transport of Wntless. In vivo suppression of Ce-tat-5 (C. elegans ATP9A ortholog) phenocopies loss of SNX3-retromer function, leading to enhanced lysosomal degradation of Wntless and Wnt signaling defects. Overexpression of an ATPase-inhibited TAT-5(E246Q) mutant also perturbed Wnt signaling, implicating phospholipid flippase activity in SNX3-retromer-mediated Wntless sorting. |
Co-immunoprecipitation, in vivo RNAi (C. elegans), ATPase-dead mutant overexpression, Wnt phenotypic assay |
Nature communications |
High |
30213940
|
| 2019 |
Knockdown of ATP9A expression in human hepatoma cells resulted in a significant increase in extracellular vesicle (EV) release. Pharmacological blocking of exosome release in ATP9A knockdown cells significantly reduced total EV numbers, supporting a role for ATP9A specifically in regulating exosome release. The increased EV release was independent of caspase-3 activation. |
siRNA knockdown, nanoparticle tracking analysis of EVs, pharmacological inhibition of exosome release |
PloS one |
Medium |
30947313
|
| 2023 |
ATP9A localizes mainly to endosomes and modulates RAB5 and RAB11 GTPase activation to regulate the endosomal recycling pathway. Atp9a null mice show decreased muscle strength, memory deficits, hyperkinetic movement disorder, abnormal neurite morphology, and impaired synaptic transmission. ATP9A pathogenic mutants (nonsense variants) have aberrant subcellular localization and cause abnormal endosomal recycling. ATP9A is required for maintaining neuronal neurite morphology and viability of neural cells in vitro. |
Atp9a knockout mouse model, primary neuron culture, subcellular localization assay, RAB5/RAB11 activation assay |
Molecular psychiatry |
High |
36604604
|
| 2023 |
ATP9A interacts with ATP6V1A (a vacuolar ATPase subunit) and facilitates its transport to the plasma membrane, promoting plasma membrane cholesterol accumulation and driving RAC1-dependent macropinocytosis in hepatocellular carcinoma cells. ATP9A is critical for regulating macropinocytosis under nutrient starvation. |
Co-immunoprecipitation, subcellular fractionation, cholesterol staining, RAC1 activation assay, macropinocytosis assay |
The Journal of pathology |
Medium |
36715683
|
| 2025 |
ATP9A and ATP9B form homomeric and/or heteromeric complexes. Both are required for transport of VSVG from the Golgi to the plasma membrane in the exocytic pathway. Flippase activities of both ATP9A and ATP9B are crucial for this transport process. Heteromeric complex formation between ATP9A and ATP9B contributes to retention of ATP9A in the Golgi. |
Co-immunoprecipitation, VSVG transport assay, flippase-activity mutants, subcellular localization |
Life science alliance |
Medium |
40234049
|
| 2025 |
Overexpression of four selected missense mutant forms of Atp9a in HeLa cells and primary neuronal cultures led to loss of mature dendritic spines. Three missense variants retained endosomal localization while one remained blocked in the endoplasmic reticulum. shRNA-mediated knockdown of ATP9A in neurons decreased the number of dendrites per neuron, demonstrating a role for ATP9A in neuronal arborization and dendritic spine maturation. |
Overexpression of mutant ATP9A in HeLa cells and primary neuronal cultures, shRNA knockdown, confocal microscopy of dendritic spines and arborization |
Human mutation |
Medium |
40226306
|
| 2025 |
Knockdown of ATP9A in human cells causes exposure of phosphatidylinositol-4-phosphate (PI4P) in the extracellular leaflet of the plasma membrane, and ATP9A expression level correlates with neomycin sensitivity. This implicates ATP9A (ortholog of yeast Neo1) in maintaining PI4P membrane asymmetry at the plasma membrane. |
siRNA knockdown, PI4P membrane asymmetry assay (extracellular leaflet detection), neomycin sensitivity assay |
bioRxivpreprint |
Medium |
bio_10.1101_2025.03.03.641220
|