GO:0000829 diphosphoinositol pentakisphosphate kinase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0000829 describes the enzymatic activity that transfers a phosphate from ATP onto diphospho-1D-myo-inositol-pentakisphosphate (PP-IP5) to produce bis(diphospho)-1D-myo-inositol-tetrakisphosphate (bis-PP-IP4), a high-energy inositol pyrophosphate.
• The enzymes carrying this activity are the diphosphoinositol pentakisphosphate kinases PPIP5K1 (VIP1) and PPIP5K2 (VIP2), which also phosphorylate IP6 to synthesize 5-IP7.
• PPIP5K1 activity is stimulated by phosphatidylinositol(4,5)bisphosphate (PIP2), linking inositol pyrophosphate synthesis to phosphoinositide signaling.
• Mutations in PPIP5K2 cause nonsyndromic hearing loss in humans and mice, demonstrating a direct role in sensory biology.
• PPIP5K1 suppresses etoposide-triggered apoptosis, implicating this activity in DNA-damage responses and cell survival.
• The catalytic output bis-PP-IP4 is a high-energy signaling molecule whose synthesis can be studied with chemoenzymatic and CRISPR-based approaches.
Description
Diphosphoinositol pentakisphosphate kinase activity (GO:0000829) is a molecular function that catalyzes the ATP-dependent phosphorylation of diphospho-1D-myo-inositol-pentakisphosphate (PP-IP5) to form bis(diphospho)-1D-myo-inositol-tetrakisphosphate (bis-PP-IP4). This reaction belongs to the inositol pyrophosphate (IP7/IP8) pathway, a family of highly phosphorylated inositol derivatives that act as signaling molecules in eukaryotes. The activity was first identified and purified from mammalian cells, establishing a distinct enzyme class that synthesizes inositol pyrophosphates. Subsequent cloning of human VIP1-like kinases showed that PPIP5K1 and PPIP5K2 are the principal enzymes with this activity, and that they also convert IP6 to 5-IP7. Because inositol pyrophosphates regulate phosphate homeostasis, vesicle trafficking, DNA repair, and apoptosis, the kinase activity encoded by GO:0000829 sits at the intersection of cellular metabolism and stress signaling. Researchers study this term to understand how cells generate high-energy inositol phosphates, how these molecules influence disease, and how the enzymes can be targeted or modeled with CRISPR. The reaction is unusual in that it consumes ATP to create a diphosphate group on an already polyphosphorylated inositol ring, giving bis-PP-IP4 a high phosphoryl-transfer potential. This makes GO:0000829 a focal point for questions about energy sensing, signal transduction, and the biochemical logic of inositol pyrophosphate synthesis.
diphosphoinositol pentakisphosphate kinase activity At A Glance
| GO ID | GO:0000829 |
|---|---|
| GO term | diphosphoinositol pentakisphosphate kinase activity |
| Ontology | molecular_function |
| Synonym | inositol heptakisphosphate kinase activity; PP-IP5 kinase activity |
| Major function | ATP-dependent phosphorylation of PP-IP5 to bis-PP-IP4 |
| Reaction | ATP + diphospho-1D-myo-inositol-pentakisphosphate = ADP + bis(diphospho)-1D-myo-inositol-tetrakisphosphate |
| Representative enzymes | PPIP5K1 (VIP1), PPIP5K2 (VIP2) |
| Pathway context | Inositol pyrophosphate biosynthesis |
| Substrate | diphospho-1D-myo-inositol-pentakisphosphate (PP-IP5) |
| Product | bis(diphospho)-1D-myo-inositol-tetrakisphosphate (bis-PP-IP4) |
What Is GO:0000829?
GO:0000829 is defined as the catalysis of the reaction ATP + diphospho-1D-myo-inositol-pentakisphosphate = ADP + bis(diphospho)-1D-myo-inositol-tetrakisphosphate. In other words, it is the kinase activity that adds a phosphate group from ATP to PP-IP5, producing the inositol pyrophosphate bis-PP-IP4. The QuickGO definition notes that the isomeric configurations of both PP-IP5 and bis-PP-IP4 are unknown, so the term captures the enzymatic activity without specifying ring positions. Synonyms include inositol heptakisphosphate kinase activity and PP-IP5 kinase activity.
Why Is diphosphoinositol pentakisphosphate kinase activity Important in Cell Biology?
GO:0000829 is important because it defines the terminal step in the synthesis of bis-PP-IP4, a high-energy inositol pyrophosphate that participates in phosphate homeostasis, DNA repair, apoptosis, and vesicle trafficking. The enzymes that carry this activity, PPIP5K1 and PPIP5K2, are also the major IP6 kinases that produce 5-IP7, so the same proteins control two connected signaling outputs. Human genetics has linked PPIP5K2 mutations to hearing loss, showing that this activity is required for normal sensory function. In cell biology, PPIP5K1 activity is regulated by PIP2, tying inositol pyrophosphate synthesis to phosphoinositide signaling at membranes. Because bis-PP-IP4 is chemically reactive and can donate phosphate groups, its synthesis is relevant to energy metabolism and stress responses. For researchers, GO:0000829 provides a precise annotation to interpret kinase screens, phosphoproteomics, and genetic models of inositol pyrophosphate signaling.
• Defines the enzymatic step that produces bis-PP-IP4, a high-energy inositol pyrophosphate.
• Enables annotation of PPIP5K1 and PPIP5K2 as the principal human enzymes with this activity.
• Connects inositol pyrophosphate synthesis to PIP2-dependent membrane signaling.
• Provides a mechanistic link to hearing loss through PPIP5K2 mutations.
• Implicates the activity in suppression of etoposide-triggered apoptosis.
• Supports studies of phosphate homeostasis and cellular energy balance.
• Offers a target for chemoenzymatic synthesis of inositol pyrophosphate standards.
• Helps interpret genetic and pharmacological perturbations of the inositol pyrophosphate pathway.
• Guides CRISPR model design for PPIP5K1 and PPIP5K2 loss- or gain-of-function.
• Provides a defined molecular function for enrichment analysis of kinase datasets.
Molecular Mechanism of diphosphoinositol pentakisphosphate kinase activity
Substrate recognition and binding of PP-IP5
In simple terms: The enzyme first grabs its substrate, PP-IP5, and positions it for phosphorylation.
Diphosphoinositol pentakisphosphate kinase activity acts on diphospho-1D-myo-inositol-pentakisphosphate (PP-IP5), an inositol pyrophosphate with a diphosphate group on the ring. The enzyme must recognize this highly charged substrate and orient it so that the terminal phosphate can accept a phosphate from ATP. Purification of the original enzyme activity showed that it selectively uses PP-IP5 as a substrate to synthesize bis-PP-IP4. The same enzymes, PPIP5K1 and PPIP5K2, also accept IP6 as a substrate to make 5-IP7, indicating a shared active site that accommodates related inositol polyphosphates. This dual substrate use means that substrate availability and competition between IP6 and PP-IP5 can influence the flux through GO:0000829.
ATP-dependent phosphoryl transfer
In simple terms: The enzyme uses ATP as a phosphate donor and attaches that phosphate to PP-IP5.
The catalytic reaction of GO:0000829 is ATP + diphospho-1D-myo-inositol-pentakisphosphate = ADP + bis(diphospho)-1D-myo-inositol-tetrakisphosphate. This is a classic kinase phosphoryl-transfer step in which the gamma-phosphate of ATP is transferred to the substrate, releasing ADP. The product, bis-PP-IP4, contains two diphosphate groups, giving it high phosphoryl-transfer potential. Because the reaction consumes ATP, the activity is sensitive to cellular energy status and to the availability of ATP in the compartment where the enzyme resides. The QuickGO definition does not specify the isomeric configuration of the product, reflecting the fact that the exact ring position of the new diphosphate has not been fully resolved.
Regulation by phosphatidylinositol(4,5)bisphosphate
In simple terms: A membrane lipid, PIP2, turns up the activity of the enzyme.
PPIP5K1 activity is regulated by phosphatidylinositol(4,5)bisphosphate (PIP2), which stimulates the synthesis of inositol pyrophosphates. This links GO:0000829 to phosphoinositide signaling and suggests that the enzyme can be recruited or activated at membranes where PIP2 is enriched. Because PIP2 is itself a signaling lipid, its effect on PPIP5K1 provides a mechanism for cross-talk between phosphoinositide and inositol pyrophosphate pathways. This regulation is important for interpreting experiments in which PIP2 levels are manipulated, since changes in PIP2 can indirectly alter bis-PP-IP4 synthesis.
Phosphatase counteractivity and phosphate homeostasis
In simple terms: The same enzyme family can also remove phosphates, balancing the pathway.
PPIP5K enzymes contain a phosphatase domain that can reverse inositol pyrophosphate phosphorylation, and a small signaling domain controls this phosphatase activity in phosphate homeostasis. This means that GO:0000829, the kinase activity, operates alongside a counteracting phosphatase activity within the same protein family. The balance between kinase and phosphatase outputs determines the steady-state levels of inositol pyrophosphates such as 5-IP7 and bis-PP-IP4. Researchers studying GO:0000829 therefore need to consider both the forward kinase reaction and the reverse dephosphorylation when interpreting cellular phenotypes.
Chemoenzymatic synthesis and product detection
In simple terms: Scientists can make the reaction product in the lab to study it.
Scalable chemoenzymatic synthesis of inositol pyrophosphates has been developed, enabling production of compounds related to the GO:0000829 reaction for biochemical and structural studies. These methods use purified enzymes to convert inositol polyphosphate precursors into pyrophosphates, providing standards for mass spectrometry and NMR. Such approaches complement genetic studies by allowing direct testing of enzyme activity and substrate specificity. They also help validate whether a candidate enzyme truly carries GO:0000829 activity in vitro.
Key Genes Involved in GO:0000829 diphosphoinositol pentakisphosphate kinase activity
The genes and proteins most directly associated with GO:0000829 are the diphosphoinositol pentakisphosphate kinases and their substrates, along with related inositol polyphosphate pathway components.
| Gene | Major Role | Research Relevance |
|---|---|---|
| PPIP5K1 | Encodes a diphosphoinositol pentakisphosphate kinase that synthesizes inositol pyrophosphates | Central enzyme for GO:0000829; regulates apoptosis and is stimulated by PIP2 |
| PPIP5K2 | Encodes a second diphosphoinositol pentakisphosphate kinase | Mutations cause hearing loss; key for genetic studies of the activity |
| VIP1 | Yeast/human VIP1-like inositol hexakisphosphate and diphosphoinositol pentakisphosphate kinase | Model enzyme for cloning and characterization of the activity |
| VIP2 | VIP1-like inositol hexakisphosphate and diphosphoinositol pentakisphosphate kinase | Second human enzyme with this activity; useful for comparative studies |
| IP6K1 | Inositol hexakisphosphate kinase that produces 5-IP7 | Upstream pathway enzyme that supplies inositol pyrophosphate precursors |
| IP6K2 | Inositol hexakisphosphate kinase family member | Contributes to inositol pyrophosphate synthesis and pathway context |
| ITPK1 | Inositol-tetrakisphosphate 1-kinase | Generates inositol polyphosphate intermediates relevant to PP-IP5 production |
| IPPK | Inositol-pentakisphosphate 2-kinase | Produces IP6, a substrate for PPIP5K enzymes |
| PLC | Phospholipase C | Generates PIP2 and IP3, influencing PPIP5K1 regulation |
| PI4K | Phosphatidylinositol 4-kinase | Supplies PIP2 precursors that regulate PPIP5K1 |
| PIP5K | Phosphatidylinositol-4-phosphate 5-kinase | Synthesizes PIP2, a regulator of GO:0000829 |
| DIPP | Diphosphoinositol polyphosphate phosphohydrolase | Degrades inositol pyrophosphates, opposing the kinase activity |
| PPIP5K1 phosphatase domain | Intrinsic phosphatase module | Controls phosphate homeostasis and balances kinase output |
| ATP | Phosphate donor | Required co-substrate for the reaction |
| PP-IP5 | Substrate | Direct substrate of GO:0000829 |
| bis-PP-IP4 | Product | High-energy inositol pyrophosphate generated by the activity |
| 5-IP7 | Related inositol pyrophosphate | Product of PPIP5K-mediated IP6 phosphorylation |
How Is diphosphoinositol pentakisphosphate kinase activity Regulated?
GO:0000829 is regulated at multiple levels. The activity of PPIP5K1 is stimulated by phosphatidylinositol(4,5)bisphosphate (PIP2), linking it to phosphoinositide signaling at membranes. The same enzyme family contains a phosphatase domain whose activity is controlled by a small signaling domain, providing an intrinsic counterbalance that affects net inositol pyrophosphate levels and phosphate homeostasis. Substrate availability also regulates flux through the reaction, since PPIP5K enzymes can use both IP6 and PP-IP5, and competition between these substrates influences product formation. In addition, cellular ATP levels and energy status can affect the kinase reaction because ATP is a required co-substrate. Finally, expression levels and localization of PPIP5K1 and PPIP5K2 determine where and when the activity occurs, and these parameters can be altered by genetic or pharmacological perturbations.
diphosphoinositol pentakisphosphate kinase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PPIP5K2 | Hearing loss | Knock-in mouse carrying patient mutation; auditory brainstem response testing |
| PPIP5K1 | Apoptosis and chemotherapy response | Knockout cell lines treated with etoposide; apoptosis assays |
| PPIP5K1/PPIP5K2 | Phosphate homeostasis | Point-mutation models of the phosphatase domain; phosphate flux assays |
| IP6K1 | Inositol pyrophosphate pathway | Knockout models to alter substrate availability for GO:0000829 |
| PPIP5K1 | PIP2-dependent signaling | Overexpression and PIP2 manipulation in cell lines |
Hearing loss and PPIP5K2 mutations
Mutations in PPIP5K2, the gene encoding a diphosphoinositol pentakisphosphate kinase, are associated with hearing loss in both humans and mice. This links GO:0000829 directly to a sensory disorder and suggests that inositol pyrophosphate synthesis is required for normal auditory function. Experimental models with PPIP5K2 mutations show hearing deficits, providing a system to study how the kinase activity protects or maintains cochlear cells. Researchers can use these models to test whether restoring the activity rescues hearing, which would strengthen the causal link between GO:0000829 and disease.
Apoptosis and DNA-damage responses
PPIP5K1 suppresses etoposide-triggered apoptosis, indicating that the kinase activity encoded by GO:0000829 promotes cell survival under DNA-damaging conditions. Etoposide is a topoisomerase inhibitor used in cancer therapy, so this finding connects the activity to chemotherapy responses. Loss of PPIP5K1 activity may sensitize cells to apoptosis, whereas increased activity may confer resistance. This makes GO:0000829 a potential modifier of cancer treatment outcomes and a target for studies of DNA-damage signaling.
Phosphate homeostasis and metabolic regulation
The phosphatase domain of PPIP5K enzymes is controlled by a small signaling domain that regulates phosphate homeostasis, placing the kinase activity of GO:0000829 in a metabolic context. Inositol pyrophosphates are sensors of phosphate and energy status, and their synthesis and degradation are tightly balanced. Dysregulation of this balance can affect cellular metabolism and stress responses. Studying GO:0000829 therefore contributes to understanding how cells maintain phosphate and energy homeostasis.
Cancer and cell signaling
Because PPIP5K1 activity suppresses apoptosis and is regulated by PIP2, it may influence cancer cell survival and phosphoinositide signaling. Inositol pyrophosphates have been implicated in cell growth and stress responses, and the enzymes that produce them are being explored as potential therapeutic targets. However, the precise role of GO:0000829 in cancer remains an active area of research, and conclusions should be drawn from experimental models rather than speculation. CRISPR models of PPIP5K1 and PPIP5K2 can help determine whether the activity is causal in specific cancer contexts.
From diphosphoinositol pentakisphosphate kinase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of PPIP5K1 reduce bis-PP-IP4 synthesis? | PPIP5K1 knockout cell line |
| Does a patient PPIP5K2 mutation impair kinase activity? | Point-mutation knock-in of the human mutation |
| Can tagged PPIP5K1 be used to monitor localization? | Knock-in of an epitope tag at the endogenous locus |
| Does overexpression of PPIP5K1 protect against apoptosis? | Overexpression cell line treated with etoposide |
| Which substrates are used by PPIP5K2? | Purified enzyme from overexpression system with IP6 and PP-IP5 |
| Does PIP2 regulate PPIP5K1 in live cells? | Knockout of PIP2 synthesis enzymes combined with activity assays |
How to Study the diphosphoinositol pentakisphosphate kinase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Kinase activity assay | Conversion of PP-IP5 to bis-PP-IP4 | Validate GO:0000829 activity in vitro |
| Mass spectrometry | Levels of inositol pyrophosphates | Quantify 5-IP7 and bis-PP-IP4 in cells |
| CRISPR knockout | Loss of gene function | Test PPIP5K1/PPIP5K2 requirement |
| Knock-in point mutation | Specific amino acid change | Model patient PPIP5K2 mutation |
| Fluorescence imaging | Protein localization | Study PIP2-dependent recruitment |
| Phosphate flux assay | Cellular phosphate handling | Assess phosphate homeostasis |
| Apoptosis assay | Cell death after etoposide | Test PPIP5K1 survival function |
| Chemoenzymatic synthesis | Production of inositol pyrophosphate standards | Generate reference compounds |
Enzymatic activity assays
Direct measurement of GO:0000829 activity uses purified enzyme or cell lysates incubated with PP-IP5 and ATP, followed by detection of bis-PP-IP4 by chromatography or mass spectrometry. These assays can test substrate specificity, kinetics, and the effect of regulators such as PIP2. Chemoenzymatic synthesis provides standards for product identification. Activity assays are essential for validating whether a candidate gene product truly carries the annotated function.
Genetic perturbation and phenotyping
Knockout, knock-in, and point-mutation models of PPIP5K1 and PPIP5K2 allow researchers to link the activity to cellular and organismal phenotypes. Hearing loss models require auditory testing, while apoptosis models use viability and caspase assays. Phosphate homeostasis can be assessed with phosphate flux and gene-expression readouts. These approaches connect GO:0000829 to disease-relevant biology.
Lipid and metabolite profiling
Because PIP2 regulates PPIP5K1, lipid profiling of phosphoinositides can reveal upstream changes that affect GO:0000829. Mass spectrometry of inositol pyrophosphates can quantify 5-IP7 and bis-PP-IP4 levels. Combining lipid and metabolite profiling provides a systems view of the pathway. This is useful when interpreting CRISPR perturbations of related genes.
Imaging and localization studies
Tagged knock-in of PPIP5K1 or PPIP5K2 enables imaging of protein localization and dynamics. Fluorescence microscopy can show whether the enzyme relocalizes to membranes enriched in PIP2. Localization data help explain how the activity is spatially regulated. These methods complement biochemical assays and genetic models.
How CRISPR Can Be Used to Study GO:0000829 diphosphoinositol pentakisphosphate kinase activity
Knockout
CRISPR knockout of PPIP5K1 or PPIP5K2 eliminates the enzymes carrying GO:0000829 activity, allowing researchers to test whether bis-PP-IP4 synthesis is required for specific phenotypes. Knockout cell lines can be challenged with etoposide to measure apoptosis, or used to quantify inositol pyrophosphate levels by mass spectrometry. Knockout models of upstream kinases such as IP6K1 can also alter substrate availability for GO:0000829. These experiments provide causal evidence linking the activity to cellular outcomes.
Point Mutation
CRISPR point mutation can introduce patient-derived mutations into PPIP5K2 to test whether they impair kinase activity and cause hearing loss phenotypes. Catalytic-dead point mutations in PPIP5K1 can separate kinase activity from other functions of the protein. Point mutations in the phosphatase domain can reveal how the counteracting activity regulates phosphate homeostasis. These models are valuable for structure-function studies of GO:0000829.
Knock-in
Knock-in of epitope tags or fluorescent proteins at the endogenous PPIP5K1 or PPIP5K2 locus enables real-time imaging and immunoprecipitation of the enzyme. Tagged knock-in avoids overexpression artifacts and preserves endogenous regulation by PIP2. Knock-in of disease-associated alleles in mice can model hearing loss and other phenotypes. These models help connect GO:0000829 to physiological function.
Overexpression
Overexpression of PPIP5K1 or PPIP5K2 increases the cellular capacity for GO:0000829 and can be used to test gain-of-function effects on apoptosis and signaling. Overexpression systems also provide material for enzyme purification and biochemical assays. However, overexpression may saturate regulatory mechanisms, so results should be interpreted alongside knockout and knock-in data. Combining overexpression with PIP2 manipulation can reveal regulatory dependencies.
How EDITGENE Supports diphosphoinositol pentakisphosphate kinase activity Research
Researchers studying diphosphoinositol pentakisphosphate kinase activity-related genes often need to determine whether a candidate gene is causally involved in inositol pyrophosphate synthesis, apoptosis, hearing loss, or phosphate homeostasis. Establishing causality requires precise genetic models that can remove, modify, or tag the enzymes carrying GO:0000829 activity without confounding off-target effects. EDITGENE provides a suite of CRISPR services designed to generate such models efficiently and reproducibly.
Contact EDITGENE today to design your custom CRISPR model for diphosphoinositol pentakisphosphate kinase activity research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| IP6K3 Knockout HEK293 Cell Line | EDJ-KQ1031 | Human | 117283 | Details Get a Quote |
| IP6K1 Knockout HEK293 Cell Line | EDJ-KQ1685 | Human | 9807 | Details Get a Quote |
| IP6K2 Knockout HEK293 Cell Line | EDJ-KQ1686 | Human | 51447 | Details Get a Quote |
| PPIP5K2 Knockout HEK293 Cell Line | EDJ-KQ1687 | Human | 23262 | Details Get a Quote |
| IP6K1 Knockout A-549 Cell Line | EDJ-KQ21474 | Human | 9807 | Details Get a Quote |
| IP6K1 Knockout HCT 116 Cell Line | EDJ-KQ21475 | Human | 9807 | Details Get a Quote |
| IP6K1 Knockout HeLa Cell Line | EDJ-KQ21476 | Human | 9807 | Details Get a Quote |
| IP6K2 Knockout A-549 Cell Line | EDJ-KQ21477 | Human | 51447 | Details Get a Quote |
| IP6K2 Knockout HCT 116 Cell Line | EDJ-KQ21478 | Human | 51447 | Details Get a Quote |
| IP6K2 Knockout HeLa Cell Line | EDJ-KQ21479 | Human | 51447 | Details Get a Quote |
| PPIP5K2 Knockout A-549 Cell Line | EDJ-KQ21481 | Human | 23262 | Details Get a Quote |
| PPIP5K2 Knockout HCT 116 Cell Line | EDJ-KQ21482 | Human | 23262 | Details Get a Quote |
| PPIP5K2 Knockout HeLa Cell Line | EDJ-KQ21483 | Human | 23262 | Details Get a Quote |
| PPIP5K1 Knockout HEK293 Cell Line | EDJ-KQ50893 | Human | 9677 | Details Get a Quote |
| PPIP5K1 Knockout HeLa Cell Line | EDJ-KQ55224 | Human | 9677 | Details Get a Quote |
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Frequently Asked Questions About diphosphoinositol pentakisphosphate kinase activity
What is diphosphoinositol pentakisphosphate kinase activity?
It is the enzymatic activity defined by GO:0000829 that uses ATP to phosphorylate PP-IP5, producing bis-PP-IP4, a high-energy inositol pyrophosphate.
What genes are involved in diphosphoinositol pentakisphosphate kinase activity?
The main human genes are PPIP5K1 and PPIP5K2, which encode the kinases that carry this activity and also phosphorylate IP6 to make 5-IP7.
What is the reaction catalyzed by GO:0000829?
The reaction is ATP + diphospho-1D-myo-inositol-pentakisphosphate = ADP + bis(diphospho)-1D-myo-inositol-tetrakisphosphate.
How is diphosphoinositol pentakisphosphate kinase activity regulated?
PPIP5K1 activity is stimulated by phosphatidylinositol(4,5)bisphosphate, and the enzyme family also has a phosphatase domain that balances phosphate homeostasis.
What diseases are linked to PPIP5K2 mutations?
Mutations in PPIP5K2 are associated with hearing loss in humans and mice.
Does PPIP5K1 affect apoptosis?
Yes, PPIP5K1 suppresses etoposide-triggered apoptosis, suggesting a role in cell survival after DNA damage.
What is bis-PP-IP4?
Bis-PP-IP4 is the product of GO:0000829, a bis(diphospho)inositol tetrakisphosphate with high phosphoryl-transfer potential.
How can I study GO:0000829 in the lab?
Common methods include kinase activity assays, mass spectrometry of inositol pyrophosphates, and CRISPR knockout or knock-in models of PPIP5K1 and PPIP5K2.
Is there a chemoenzymatic way to make inositol pyrophosphates?
Yes, scalable chemoenzymatic synthesis has been developed to produce inositol pyrophosphate standards for research.
What model systems are used for PPIP5K2 hearing loss?
Mouse models carrying PPIP5K2 mutations and patient-derived cells are used to study hearing loss phenotypes.
Conclusion
GO:0000829, diphosphoinositol pentakisphosphate kinase activity, defines a specific enzymatic step in inositol pyrophosphate biology: the ATP-dependent conversion of PP-IP5 to bis-PP-IP4. The enzymes PPIP5K1 and PPIP5K2 carry this activity and also produce 5-IP7, placing them at the center of a signaling pathway that influences apoptosis, hearing, and phosphate homeostasis. Regulation by PIP2 and the presence of an intrinsic phosphatase domain add layers of control that researchers must consider when designing experiments. CRISPR-based knockout, point-mutation, knock-in, and overexpression models provide the tools needed to test causality and to explore therapeutic hypotheses. As the field advances, precise annotation of GO:0000829 will remain essential for interpreting genomic and biochemical data on inositol pyrophosphate signaling.
References
- 1. Nair VS et al.. 2018. Inositol Pyrophosphate Synthesis by Diphosphoinositol Pentakisphosphate Kinase-1 is Regulated by Phosphatidylinositol(4,5)bisphosphate.. Biosci Rep 38(2) PMID: 29459425
- 2. Yousaf R et al.. 2018. Mutations in Diphosphoinositol-Pentakisphosphate Kinase PPIP5K2 are associated with hearing loss in human and mouse.. PLoS Genet 14(3):e1007297 PMID: 29590114
- 3. Huang CF et al.. 1998. Identification and purification of diphosphoinositol pentakisphosphate kinase, which synthesizes the inositol pyrophosphate bis(diphospho)inositol tetrakisphosphate.. Biochemistry 37(42):14998-5004 PMID: 9778378
- 4. Machkalyan G et al.. 2016. PPIP5K1 Suppresses Etoposide-triggered Apoptosis.. J Mol Signal 11:4 PMID: 31051014
- 5. Puschmann R et al.. 2019. Scalable Chemoenzymatic Synthesis of Inositol Pyrophosphates.. Biochemistry 58(38):3927-3932 PMID: 31461621
- 6. Fridy PC et al.. 2007. Cloning and characterization of two human VIP1-like inositol hexakisphosphate and diphosphoinositol pentakisphosphate kinases.. J Biol Chem 282(42):30754-62 PMID: 17690096
- 7. Raia P et al.. 2025. A small signaling domain controls PPIP5K phosphatase activity in phosphate homeostasis.. Nat Commun 16(1):1753 PMID: 39966396
- 8. Saiardi A et al.. 1999. Synthesis of diphosphoinositol pentakisphosphate by a newly identified family of higher inositol polyphosphate kinases.. Curr Biol 9(22):1323-6 PMID: 10574768
