GO:0034595 phosphatidylinositol phosphate 5-phosphatase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0034595 describes the enzymatic removal of the 5-phosphate group from phosphatidylinositol phosphate lipids, a reaction that terminates or redirects phosphoinositide signaling.
• The reaction is catalyzed by inositol polyphosphate 5-phosphatases such as INPP5D (SHIP1), INPPL1 (SHIP2), OCRL, INPP5B, INPP5E, INPP5J, INPP5K, SYNJ1 and SYNJ2, which dephosphorylate substrates including PI(3,4,5)P3, PI(4,5)P2 and PI(3,5)P2.
• Loss of 5-phosphatase activity causes accumulation of PI(3,4,5)P3 and PI(4,5)P2, altering Akt signaling, autophagy, lysosome reformation, ciliary protein dosage and skeletal development.
• Human disease links include opsismodysplasia (INPPL1), Lowe syndrome and Dent disease (OCRL), Joubert syndrome (INPP5E), and skeletal muscle disease from defective lysosome reformation.
• The C2 domain and anionic lipid environment regulate SHIP1/SHIP2 catalytic activity, making 5-phosphatases context-dependent signaling nodes.
• CRISPR knockout, point-mutation, knock-in and overexpression models are essential to dissect which 5-phosphatase controls a given phosphoinositide pool and phenotype.
Description
Phosphatidylinositol phosphate 5-phosphatase activity (GO:0034595) is a molecular function that removes the phosphate at the 5-position of phosphatidylinositol phosphate lipids, thereby converting one phosphoinositide species into another and switching off or rerouting downstream signals. This activity is central to phosphoinositide metabolism because PI(3,4,5)P3, PI(4,5)P2 and PI(3,5)P2 act as membrane landmarks that recruit effector proteins to control cell growth, membrane trafficking and autophagy. Researchers study GO:0034595 because the enzymes carrying it, including SHIP1, SHIP2, OCRL, INPP5E and INPP5K, are mutated in human developmental, renal, ciliary and neuromuscular disorders. The reaction is not a simple housekeeping step; its substrate specificity, membrane recruitment and regulation by protein domains and lipids determine whether a cell survives, proliferates or degrades damaged organelles. Consequently, GO:0034595 sits at the intersection of signal transduction, organelle biology and disease genetics, and it is a frequent target for CRISPR-based functional genomics.
phosphatidylinositol phosphate 5-phosphatase activity At A Glance
| GO ID | GO:0034595 |
|---|---|
| GO term | phosphatidylinositol phosphate 5-phosphatase activity |
| Ontology | molecular_function |
| Synonym | phosphoinositide 5-phosphatase activity; polyphosphoinositol lipid 5-phosphatase activity |
| Definition | Catalysis of the removal of the 5-phosphate group of a phosphatidylinositol phosphate |
| Major function | Terminates or redirects phosphoinositide signaling by dephosphorylating PI(3,4,5)P3, PI(4,5)P2 and PI(3,5)P2 |
| Representative enzymes | INPP5D (SHIP1), INPPL1 (SHIP2), OCRL, INPP5B, INPP5E, INPP5J, INPP5K, SYNJ1, SYNJ2 |
| Key substrates | PI(3,4,5)P3, PI(4,5)P2, PI(3,5)P2, inositol polyphosphates |
| Disease examples | Opsismodysplasia, Lowe syndrome, Joubert syndrome, skeletal muscle disease |
| Research methods | CRISPR KO/point mutation/knock-in, lipid mass spectrometry, live-cell lipid biosensors, Ribo-seq, RNA-seq |
What Is GO:0034595?
GO:0034595, phosphatidylinositol phosphate 5-phosphatase activity, is defined as catalysis of the removal of the 5-phosphate group of a phosphatidylinositol phosphate. In practical terms, the enzyme hydrolyzes the phosphate ester at carbon 5 of the inositol ring of a phosphoinositide lipid, releasing inorganic phosphate and leaving a phosphatidylinositol phosphate with one fewer phosphate. This activity is also called phosphoinositide 5-phosphatase activity or polyphosphoinositol lipid 5-phosphatase activity. It is a molecular_function term in the Gene Ontology and should not be confused with 3-phosphatase or 4-phosphatase activities, which remove phosphate from different positions and produce different lipid products.
Why Is phosphatidylinositol phosphate 5-phosphatase activity Important in Cell Biology?
GO:0034595 matters because the 5-phosphate position is a decisive switch in phosphoinositide signaling: removing it converts PI(3,4,5)P3 into PI(3,4)P2, PI(4,5)P2 into PI4P, or PI(3,5)P2 into PI3P, each of which recruits a different set of effector proteins. This switch controls Akt activation, autophagy, lysosome reformation, ciliary membrane composition and skeletal mineralization, so its dysregulation produces diseases ranging from opsismodysplasia to Lowe syndrome and Joubert syndrome. Because the same enzymatic activity is shared by many enzymes with distinct localization and regulation, researchers must use precise genetic models to assign function to a specific 5-phosphatase.
• Controls the balance between PI(3,4,5)P3 and PI(3,4)P2, thereby tuning Akt-dependent growth and survival signaling.
• Regulates PI(4,5)P2 pools that govern actin dynamics, endocytosis and membrane identity.
• Supports autophagy and lysosome reformation; defective lysosome reformation causes skeletal muscle disease.
• Maintains ciliary phosphoinositide composition and polycystin dosage in primary cilia.
• Mutations in INPPL1 cause opsismodysplasia, a severe skeletal dysplasia.
• Mutations in OCRL cause Lowe syndrome and Dent disease through altered phosphoinositide turnover.
• Mutations in INPP5E cause Joubert syndrome and ciliary signaling defects.
• SHIP1 and SHIP2 activity is modulated by the C2 domain and anionic lipids, making it context-dependent.
• Plant 5-phosphatases are required for seedling growth, showing evolutionary conservation.
• The activity is a tractable target for CRISPR screens that map phosphoinositide-dependent phenotypes.
Molecular Mechanism of phosphatidylinositol phosphate 5-phosphatase activity
Substrate recognition and membrane recruitment
In simple terms: The enzyme must first find the right lipid in the membrane before it can cut the phosphate.
5-phosphatases act on phosphatidylinositol phosphates embedded in membranes, so their activity depends on recruitment to specific membrane compartments. SHIP1 and SHIP2 are recruited to membranes where their substrates PI(3,4,5)P3 and PI(4,5)P2 reside, and the C2 domain contributes to this membrane interaction and to regulation of catalysis. Anionic lipids influence SHIP2 activity toward PI(3,4,5)P3, indicating that the lipid environment itself modulates the reaction. In primary cilia, a ciliary phosphoinositide pathway controls the dosage of polycystins, linking 5-phosphatase-dependent lipid composition to ciliary protein trafficking.
Catalytic removal of the 5-phosphate
In simple terms: The enzyme hydrolyzes the bond holding the 5-phosphate, releasing phosphate and changing the lipid's identity.
The defining chemical event of GO:0034595 is hydrolysis of the phosphate ester at the 5-position of the inositol ring of a phosphatidylinositol phosphate. This converts PI(3,4,5)P3 to PI(3,4)P2, PI(4,5)P2 to PI4P, or PI(3,5)P2 to PI3P, depending on the substrate and enzyme. The reaction terminates or redirects signaling because the product lacks the 5-phosphate that specific effector domains read. The catalytic mechanism is shared across inositol polyphosphate 5-phosphatases, but substrate specificity and subcellular localization differ among family members.
Regulation by protein domains and lipids
In simple terms: Accessory domains and surrounding lipids act like dimmer switches on the enzyme.
The C2 domain of SHIP1 and SHIP2 regulates inositol 5-phosphatase activity, so domain-dependent conformational changes can enhance or restrain catalysis. Anionic lipids also influence SHIP2 phosphatidylinositol 3,4,5-trisphosphate 5-phosphatase activity, showing that membrane composition is a regulatory input. These features mean that measuring GO:0034595 activity in vitro requires attention to lipid composition and protein domain context.
Downstream consequences for signaling and organelles
In simple terms: Once the 5-phosphate is removed, the cell's signaling and recycling machinery changes behavior.
By lowering PI(3,4,5)P3, 5-phosphatases attenuate Akt pathway output and alter cell growth and survival decisions. By controlling PI(4,5)P2 and PI(3,5)P2, they influence endocytosis, autophagy and lysosome reformation; defective lysosome reformation during autophagy causes skeletal muscle disease. In cilia, phosphoinositide composition regulated through this pathway controls polycystin dosage, connecting GO:0034595 to ciliary signaling. Plant 5-phosphatases are required for seedling growth, indicating that the downstream consequences of this activity extend beyond animal cells.
Key Genes Involved in GO:0034595 phosphatidylinositol phosphate 5-phosphatase activity
The following genes encode enzymes or pathway components directly associated with phosphatidylinositol phosphate 5-phosphatase activity and its biological readouts.
| Gene | Major Role | Research Relevance |
|---|---|---|
| INPP5D (SHIP1) | Hydrolyzes PI(3,4,5)P3 to PI(3,4)P2 in hematopoietic cells | C2 domain regulates 5-phosphatase activity; immune signaling models |
| INPPL1 (SHIP2) | Hydrolyzes PI(3,4,5)P3 and is sensitive to anionic lipids | Opsismodysplasia and metabolic signaling; lipid-dependent activity assays |
| OCRL | 5-phosphatase acting on PI(4,5)P2 and PI(3,4,5)P3 | Lowe syndrome and Dent disease models |
| INPP5B | 5-phosphatase with overlapping functions in membrane trafficking | Compensation studies with OCRL |
| INPP5E | Ciliary 5-phosphatase controlling phosphoinositide composition | Joubert syndrome and ciliary polycystin dosage |
| INPP5J | 5-phosphatase regulating PI(3,4,5)P3 in specific tissues | Signaling and membrane trafficking studies |
| INPP5K | 5-phosphatase linked to autophagy and muscle biology | Skeletal muscle disease and autophagy models |
| SYNJ1 | Synaptojanin 1, a polyphosphoinositide 5-phosphatase | Synaptic vesicle recycling and phosphoinositide turnover |
| SYNJ2 | Synaptojanin 2, 5-phosphatase acting on phosphoinositides | Membrane dynamics and signaling studies |
| PIK3CA | Generates PI(3,4,5)P3, the substrate of 5-phosphatases | Upstream input into GO:0034595-dependent signaling |
| PTEN | 3-phosphatase that opposes PI(3,4,5)P3 accumulation | Contrasts 3-phosphatase and 5-phosphatase activities |
| AKT1 | Effector whose recruitment depends on PI(3,4,5)P3 | Readout of 5-phosphatase activity |
| PKD1 | Polycystin-1 whose ciliary dosage is phosphoinositide-dependent | Ciliary phosphoinositide pathway models |
| PKD2 | Polycystin-2 whose ciliary dosage is phosphoinositide-dependent | Ciliary phosphoinositide pathway models |
| SQSTM1 | Autophagy receptor relevant to lysosome reformation phenotypes | Autophagy and muscle disease models |
| MAP1LC3B | Autophagosome marker used to monitor autophagy flux | Autophagy readouts in 5-phosphatase models |
| BECN1 | Autophagy regulator connected to phosphoinositide signaling | Autophagy pathway studies |
| ATG7 | Core autophagy gene required for autophagosome formation | Autophagy context for 5-phosphatase phenotypes |
How Is phosphatidylinositol phosphate 5-phosphatase activity Regulated?
GO:0034595 activity is regulated at multiple levels. Protein domains such as the C2 domain of SHIP1 and SHIP2 modulate inositol 5-phosphatase activity, so conformational control is intrinsic to these enzymes. The lipid environment is a second layer: anionic lipids influence SHIP2 phosphatidylinositol 3,4,5-trisphosphate 5-phosphatase activity, meaning membrane composition can tune the reaction. Upstream phosphoinositide 3-kinase signaling generates the PI(3,4,5)P3 substrate, so the balance between 3-kinase and 5-phosphatase activities determines net lipid output. Autophagy and lysosome reformation pathways intersect with 5-phosphatase function, and defective lysosome reformation during autophagy causes skeletal muscle disease, indicating that organelle state feeds back on this activity. In cilia, a phosphoinositide pathway regulates polycystin dosage, showing that compartment-specific regulation of 5-phosphatase activity controls protein trafficking.
phosphatidylinositol phosphate 5-phosphatase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| INPPL1 | Opsismodysplasia, skeletal dysplasia | Knockout and point-mutation cell models; lipid profiling |
| INPP5E | Joubert syndrome, ciliary signaling defects | Knockout and tagged knock-in ciliary models |
| OCRL | Lowe syndrome, Dent disease | Knockout and overexpression models with lipid biosensors |
| INPP5K | Skeletal muscle disease, defective lysosome reformation | Knockout muscle cell models and autophagy flux assays |
| SHIP1/SHIP2 | Immune and metabolic signaling, lipid-dependent catalysis | Point-mutation models targeting C2 domain regulation |
Opsismodysplasia and skeletal dysplasia
INPPL1-related opsismodysplasia is a skeletal disorder caused by impaired SHIP2 function, linking phosphatidylinositol phosphate 5-phosphatase activity to bone development. Because SHIP2 hydrolyzes PI(3,4,5)P3 and is regulated by anionic lipids, loss of its activity alters phosphoinositide-dependent signaling in skeletal cells. Experimental models of INPPL1 dysfunction are therefore used to understand how 5-phosphatase activity controls skeletal mineralization and growth.
Ciliopathies and ciliary signaling
A ciliary phosphoinositide pathway regulates the dosage of polycystins in primary cilia, connecting 5-phosphatase-dependent lipid composition to ciliary protein trafficking. INPP5E is a ciliary 5-phosphatase, and its dysfunction is associated with Joubert syndrome and related ciliary phenotypes. These findings place GO:0034595 within the molecular machinery that maintains ciliary membrane identity and signaling.
Autophagy, lysosome reformation and muscle disease
Defective lysosome reformation during autophagy causes skeletal muscle disease, and phosphoinositide turnover is required for this process. 5-phosphatases such as INPP5K contribute to autophagy and muscle biology, so their loss can impair lysosome reformation and muscle function. Broader autophagy dysfunction is associated with neurodevelopmental, neuromuscular and neurodegenerative disorders, providing context for 5-phosphatase-related phenotypes.
Renal and syndromic disease
OCRL 5-phosphatase activity is required for normal phosphoinositide turnover, and its loss is linked to Lowe syndrome and Dent disease. These disorders show that removing the 5-phosphate from phosphatidylinositol phosphates is essential for renal and neurological function. Studying OCRL and related 5-phosphatases in cell and animal models helps define which phosphoinositide pools depend on this activity.
From phosphatidylinositol phosphate 5-phosphatase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of a 5-phosphatase alter PI(3,4,5)P3 levels? | CRISPR knockout cell line with lipid mass spectrometry |
| Does a disease variant change catalytic activity? | Point-mutation knock-in of the patient variant |
| Where does the enzyme act in the cell? | Tagged knock-in with live-cell imaging |
| Does overexpression phenocopy lipid depletion? | Inducible overexpression cell model |
| Which autophagy steps require 5-phosphatase activity? | Knockout plus autophagy flux reporters |
| How does the C2 domain regulate catalysis? | Domain point-mutation and lipid-dependent activity assays |
How to Study the phosphatidylinositol phosphate 5-phosphatase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Lipid mass spectrometry | Phosphoinositide species abundance | Detect PI(3,4,5)P3 to PI(3,4)P2 conversion |
| Live-cell lipid biosensors | Spatiotemporal phosphoinositide changes | Map where 5-phosphatase activity acts |
| CRISPR knockout | Loss-of-function phenotype | Assign function to a specific 5-phosphatase |
| Point-mutation knock-in | Effect of disease variant on catalysis | Test INPPL1 or SHIP2 variants |
| Autophagy flux assay | Autophagosome and lysosome dynamics | Link 5-phosphatase to lysosome reformation |
| Ciliary protein dosage assay | Polycystin levels in primary cilia | Study ciliary phosphoinositide pathway |
| RNA-seq | Transcriptional consequences | Identify downstream networks |
| Proteomics | Protein abundance and interactions | Define signaling complexes around 5-phosphatases |
Lipid mass spectrometry and biosensors
Because GO:0034595 changes the phosphorylation state of phosphatidylinositol phosphates, direct measurement of lipid species by mass spectrometry is a primary method. Live-cell phosphoinositide biosensors complement this by reporting where PI(3,4,5)P3, PI(4,5)P2 or PI(3,5)P2 change after genetic perturbation. These approaches are essential when testing whether a specific 5-phosphatase controls a defined lipid pool.
CRISPR functional genomics and screens
CRISPR knockout and point-mutation models allow researchers to remove or alter a single 5-phosphatase and measure the consequences for signaling and organelle biology. Library screening can identify which 5-phosphatases or pathway genes modify a phenotype such as autophagy flux or ciliary protein dosage. Bioinformatics analysis then integrates screen hits with phosphoinositide pathway annotations.
Autophagy and lysosome assays
Autophagy flux reporters and lysosome reformation assays measure the downstream consequences of altered 5-phosphatase activity. Because defective lysosome reformation during autophagy causes skeletal muscle disease, muscle cell models are particularly informative. These assays connect molecular lipid changes to organelle-level phenotypes.
Transcriptomics and proteomics
RNA-seq and proteomics can reveal how loss of a 5-phosphatase reshapes signaling networks and gene expression. In ciliary models, protein dosage measurements such as polycystin levels link phosphoinositide composition to trafficking. Combining these datasets with lipid measurements provides a multi-layer view of GO:0034595 function.
How CRISPR Can Be Used to Study GO:0034595 phosphatidylinositol phosphate 5-phosphatase activity
Knockout
CRISPR knockout of a 5-phosphatase gene removes the enzyme and reveals which phosphoinositide pools and phenotypes depend on GO:0034595. Knockout models are used for INPPL1, INPP5E, OCRL and INPP5K to study skeletal, ciliary, renal and muscle biology. Lipid mass spectrometry and biosensors then quantify the resulting lipid changes.
Point Mutation
Point-mutation knock-in introduces a specific disease-associated or catalytic-residue variant while preserving endogenous expression. This is important for SHIP1 and SHIP2 because the C2 domain regulates 5-phosphatase activity, so domain mutations can separate catalysis from regulation. INPPL1 variants linked to opsismodysplasia can be modeled to test their effect on enzyme function.
Knock-in
Tagged knock-in of a 5-phosphatase allows localization and interaction studies under endogenous regulation. In ciliary models, tagged knock-in helps determine where phosphoinositide turnover occurs relative to polycystin trafficking. Knock-in reporters can also be combined with lipid biosensors to correlate enzyme position with substrate conversion.
Overexpression
Overexpression of a wild-type or mutant 5-phosphatase tests whether increased activity is sufficient to deplete a specific phosphoinositide and change cell behavior. Because anionic lipids influence SHIP2 activity, overexpression experiments should control membrane lipid context. Overexpression complements knockout by showing gain-of-function effects on signaling and organelle dynamics.
How EDITGENE Supports phosphatidylinositol phosphate 5-phosphatase activity Research
Researchers studying phosphatidylinositol phosphate 5-phosphatase activity-related genes often need to determine whether a candidate gene is causally involved in a phosphoinositide-dependent phenotype, and the cleanest way to establish causality is to engineer precise genetic models in relevant cell types.
Contact EDITGENE today to design your custom CRISPR model for phosphatidylinositol phosphate 5-phosphatase activity research.
Frequently Asked Questions About phosphatidylinositol phosphate 5-phosphatase activity
What is phosphatidylinositol phosphate 5-phosphatase activity?
It is the enzymatic removal of the 5-phosphate group from a phosphatidylinositol phosphate, defined in the Gene Ontology as GO:0034595.
What does GO:0034595 mean?
GO:0034595 is the molecular_function term for catalysis of 5-phosphate removal from phosphatidylinositol phosphates, also called phosphoinositide 5-phosphatase activity.
What genes are involved in phosphatidylinositol phosphate 5-phosphatase activity?
Key genes include INPP5D (SHIP1), INPPL1 (SHIP2), OCRL, INPP5B, INPP5E, INPP5J, INPP5K, SYNJ1 and SYNJ2.
Which diseases are linked to 5-phosphatase dysfunction?
Opsismodysplasia, Lowe syndrome, Dent disease, Joubert syndrome and skeletal muscle disease have been linked to defective 5-phosphatase function.
How is phosphatidylinositol phosphate 5-phosphatase activity regulated?
It is regulated by protein domains such as the C2 domain of SHIP1 and SHIP2 and by the anionic lipid environment of the membrane.
What substrates do 5-phosphatases act on?
They act on phosphatidylinositol phosphates including PI(3,4,5)P3, PI(4,5)P2 and PI(3,5)P2, converting them to lipids lacking the 5-phosphate.
Why is 5-phosphatase activity important for autophagy?
Phosphoinositide turnover supports autophagy and lysosome reformation, and defective lysosome reformation during autophagy causes skeletal muscle disease.
How do researchers measure phosphatidylinositol phosphate 5-phosphatase activity?
They use lipid mass spectrometry, live-cell phosphoinositide biosensors, autophagy flux assays and ciliary protein dosage assays in CRISPR-engineered cells.
What CRISPR models are used to study GO:0034595?
Knockout, point-mutation, knock-in and overexpression models are used to test loss- and gain-of-function effects on phosphoinositide signaling.
Is phosphatidylinositol phosphate 5-phosphatase activity conserved in plants?
Yes, a phosphatidylinositol phosphate-specific myo-inositol polyphosphate 5-phosphatase is required for seedling growth in plants.
Conclusion
GO:0034595, phosphatidylinositol phosphate 5-phosphatase activity, is a compact but powerful molecular function that shapes phosphoinositide signaling by removing the 5-phosphate from lipids such as PI(3,4,5)P3, PI(4,5)P2 and PI(3,5)P2. Its importance is demonstrated by human disorders including opsismodysplasia, Lowe syndrome, Dent disease, Joubert syndrome and skeletal muscle disease, each tied to specific 5-phosphatase genes and cellular contexts. Because multiple enzymes share this activity but differ in localization and regulation, precise CRISPR models combined with lipid and organelle assays are the most reliable way to assign function. Continued work on GO:0034595 will clarify how phosphoinositide switches control growth, trafficking and autophagy in health and disease.
References
- 1. Deneubourg C et al.. 2022. The spectrum of neurodevelopmental, neuromuscular and neurodegenerative disorders due to defective autophagy.. Autophagy 18(3):496-517 PMID: 34130600
- 2. Adam MP et al.. 1993. INPPL1-Related Opsismodysplasia.. PMID: 40504975
- 3. Zhang X et al.. 1998. Phosphatidylinositol signalling reactions.. Semin Cell Dev Biol 9(2):153-60 PMID: 9599410
- 4. Chen C et al.. 2026. A Ciliary Phosphoinositide Pathway Regulates the Dosage of Polycystins in Primary Cilia.. J Am Soc Nephrol 37(5):944-958 PMID: 41563398
- 5. McGrath MJ et al.. 2021. Defective lysosome reformation during autophagy causes skeletal muscle disease.. J Clin Invest 131(1) PMID: 33119550
- 6. Ercetin ME et al.. 2008. A phosphatidylinositol phosphate-specific myo-inositol polyphosphate 5-phosphatase required for seedling growth.. Plant Mol Biol 67(4):375-88 PMID: 18392779
- 7. Bradshaw WJ et al.. 2024. Regulation of inositol 5-phosphatase activity by the C2 domain of SHIP1 and SHIP2.. Structure 32(4):453-466.e6 PMID: 38309262
- 8. Vandeput F et al.. 2006. The influence of anionic lipids on SHIP2 phosphatidylinositol 3,4,5-trisphosphate 5-phosphatase activity.. Cell Signal 18(12):2193-9 PMID: 16824732
