GO:0000824 inositol-1,4,5,6-tetrakisphosphate 3-kinase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0000824 describes the enzymatic activity that converts 1D-myo-inositol 1,4,5,6-tetrakisphosphate to 1D-myo-inositol 1,3,4,5,6-pentakisphosphate using ATP.
• This 3-kinase activity is biochemically distinct from inositol 1,4,5-trisphosphate 3-kinase, as shown in rat liver.
• Inositol polyphosphate multikinase (IPMK) is a key enzyme that regulates inositol 1,4,5,6-tetrakisphosphate levels.
• The reaction product, inositol pentakisphosphate, contributes to nuclear signaling and transcriptional control.
• Plant orthologs such as Arabidopsis inositol polyphosphate 6-/3-kinase are nuclear proteins that can complement yeast transcription complex mutants.
• Dysregulation of inositol polyphosphate signaling has been linked to cancer cell growth and tumorigenicity.
Description
Inositol-1,4,5,6-tetrakisphosphate 3-kinase activity (GO:0000824) is a molecular function that catalyzes the ATP-dependent phosphorylation of 1D-myo-inositol 1,4,5,6-tetrakisphosphate at the 3-position, yielding 1D-myo-inositol 1,3,4,5,6-pentakisphosphate, ADP, and a proton. This activity was first characterized in rat liver, where it was shown to be distinct from the well-known inositol 1,4,5-trisphosphate 3-kinase. The enzyme belongs to the inositol polyphosphate kinase family and is often referred to as inositol polyphosphate multikinase (IpmK). Researchers study this activity because it sits at a critical node in inositol phosphate metabolism, linking lipid-derived second messengers to nuclear signaling events. The product, inositol pentakisphosphate, serves as a precursor for higher inositol pyrophosphates and participates in transcriptional regulation. In human intestinal epithelial cells, inositol 1,4,5,6-tetrakisphosphate produced in response to Salmonella invasion can inhibit phosphoinositide 3-kinase signaling pathways, highlighting a role in host-pathogen interactions. In plants, the Arabidopsis inositol polyphosphate 6-/3-kinase is a nuclear protein that complements yeast mutants lacking a functional ArgR-Mcm1 transcription complex, underscoring the evolutionary conservation of this activity in transcriptional control. Pharmacological inhibition of PI 3-kinase with novel antagonists has been shown to inhibit cell growth and tumorigenicity in human cancer cell lines, suggesting that targeting inositol phosphate kinases may have therapeutic potential. Thus, GO:0000824 represents a key enzymatic step connecting inositol phosphate metabolism to diverse cellular processes, from transcription to cancer biology.
inositol-1,4,5,6-tetrakisphosphate 3-kinase activity At A Glance
| GO ID | GO:0000824 |
|---|---|
| GO term | inositol-1,4,5,6-tetrakisphosphate 3-kinase activity |
| Ontology | molecular_function |
| Synonym | 1D-myo-inositol-tetrakisphosphate 3-kinase activity; inositol 1,4,5,6-tetrakisphosphate 3-kinase activity; inositol polyphosphate multikinase activity; inositol tetrakisphosphate 3-kinase activity; IpmK |
| Definition | Catalysis of the reaction: 1D-myo-inositol 1,4,5,6-tetrakisphosphate + ATP = 1D-myo-inositol 1,3,4,5,6-pentakisphosphate + ADP + H+. |
| Major function | Phosphorylation of inositol tetrakisphosphate to generate inositol pentakisphosphate, a precursor for inositol pyrophosphates and a regulator of nuclear signaling. |
| EC number | Not specified in QuickGO for this term. |
| Related activity | Distinct from inositol 1,4,5-trisphosphate 3-kinase. |
What Is GO:0000824?
In my own words, GO:0000824 describes the catalytic activity of an enzyme that transfers a phosphate group from ATP to the 3-hydroxyl position of 1D-myo-inositol 1,4,5,6-tetrakisphosphate. This reaction produces 1D-myo-inositol 1,3,4,5,6-pentakisphosphate, ADP, and a hydrogen ion. The activity is also known as inositol polyphosphate multikinase activity or IpmK.
Why Is inositol-1,4,5,6-tetrakisphosphate 3-kinase activity Important in Cell Biology?
This activity is important because it generates inositol pentakisphosphate, a molecule that serves as a precursor for higher inositol pyrophosphates and plays roles in transcriptional regulation, cell growth, and host-pathogen interactions. Understanding GO:0000824 helps researchers dissect how inositol phosphate signaling contributes to normal physiology and disease, particularly cancer and infectious diseases.
• Generates inositol pentakisphosphate, a key precursor for inositol pyrophosphates involved in cellular signaling.
• Regulates nuclear processes such as transcription through the ArgR-Mcm1 complex in yeast and plants.
• Modulates phosphoinositide 3-kinase signaling during bacterial invasion in human intestinal epithelial cells.
• Its product can influence cell growth and tumorigenicity, making it a potential target in cancer research.
• Biochemically distinct from inositol 1,4,5-trisphosphate 3-kinase, allowing specific targeting.
• Conserved across eukaryotes, from yeast to plants to humans, facilitating model organism studies.
• Involved in the regulation of inositol 1,4,5,6-tetrakisphosphate levels by inositol polyphosphate multikinase.
• Provides a node for crosstalk between lipid and soluble inositol phosphate signaling pathways.
Molecular Mechanism of inositol-1,4,5,6-tetrakisphosphate 3-kinase activity
Substrate Recognition and Binding
In simple terms: The enzyme grabs the inositol tetrakisphosphate molecule and positions it for phosphorylation.
The enzyme specifically binds 1D-myo-inositol 1,4,5,6-tetrakisphosphate as its primary substrate. This binding is stereospecific, as the 3-kinase activity is distinct from inositol 1,4,5-trisphosphate 3-kinase, which acts on a different inositol phosphate. In rat liver, the enzyme was shown to phosphorylate inositol 1,4,5,6-tetrakisphosphate but not inositol 1,4,5-trisphosphate, indicating strict substrate specificity. The enzyme likely undergoes conformational changes upon substrate binding to facilitate catalysis.
Catalytic Phosphorylation
In simple terms: The enzyme transfers a phosphate from ATP onto the inositol ring, creating a new product.
The catalytic mechanism involves the transfer of the gamma-phosphate from ATP to the 3-hydroxyl group of 1D-myo-inositol 1,4,5,6-tetrakisphosphate. This reaction yields 1D-myo-inositol 1,3,4,5,6-pentakisphosphate, ADP, and a proton. The enzyme is classified as a 3-kinase because it adds the phosphate at the 3-position of the inositol ring. This activity was first described in rat liver and later attributed to inositol polyphosphate multikinase (IpmK) in other systems.
Product Formation and Release
In simple terms: The newly formed inositol pentakisphosphate is released to perform its cellular roles.
After catalysis, the product 1D-myo-inositol 1,3,4,5,6-pentakisphosphate is released. This molecule can be further phosphorylated to inositol pyrophosphates or act as a signaling molecule itself. In human intestinal epithelial cells, inositol 1,4,5,6-tetrakisphosphate (the substrate) can inhibit phosphoinositide 3-kinase signaling, but the product of this enzyme, inositol pentakisphosphate, has distinct roles in nuclear signaling. The product is also a precursor for inositol hexakisphosphate (IP6) and inositol pyrophosphates, which regulate various cellular processes.
Regulation by Inositol Polyphosphate Multikinase
In simple terms: The enzyme IpmK controls the levels of the substrate and product, acting as a regulatory hub.
Inositol polyphosphate multikinase (IpmK) is a key enzyme that regulates inositol 1,4,5,6-tetrakisphosphate levels. Studies in yeast and mammalian cells have shown that IpmK can phosphorylate multiple inositol phosphates, including inositol 1,4,5,6-tetrakisphosphate, to generate higher inositol phosphates. This regulation is critical for maintaining cellular inositol phosphate homeostasis and for downstream signaling events. The activity of IpmK itself may be regulated by cellular localization and interaction with other proteins.
Nuclear Localization and Transcriptional Control
In simple terms: The enzyme and its product can enter the nucleus to influence gene expression.
In yeast and plants, inositol polyphosphate kinases, including the 6-/3-kinase, are nuclear proteins that complement mutants lacking a functional ArgR-Mcm1 transcription complex. This suggests that the 3-kinase activity and its product, inositol pentakisphosphate, play a role in transcriptional regulation. In yeast, the nuclear inositol 1,4,5-trisphosphate kinase (which can also act on inositol tetrakisphosphate) is involved in transcriptional control. Thus, the activity of GO:0000824 can influence gene expression programs through nuclear signaling.
Key Genes Involved in GO:0000824 inositol-1,4,5,6-tetrakisphosphate 3-kinase activity
The following genes and proteins are involved in or regulate inositol-1,4,5,6-tetrakisphosphate 3-kinase activity, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| IPMK (human) | Inositol polyphosphate multikinase; phosphorylates inositol 1,4,5,6-tetrakisphosphate | Regulates inositol phosphate levels; linked to cancer and signaling |
| IpmK (yeast) | Inositol polyphosphate multikinase; regulates inositol 1,4,5,6-tetrakisphosphate | Model for studying inositol phosphate signaling and transcription |
| IP6K (human) | Inositol hexakisphosphate kinase; produces inositol pyrophosphates | Downstream of inositol pentakisphosphate; involved in cellular energetics |
| IP3K (rat) | Inositol 1,4,5-trisphosphate 3-kinase; distinct from the tetrakisphosphate 3-kinase | Used to differentiate substrate specificity |
| AtIPK2 (Arabidopsis) | Inositol polyphosphate 6-/3-kinase; nuclear protein | Complements yeast transcription complex mutants; plant model |
| ArgR-Mcm1 complex (yeast) | Transcription complex regulated by inositol phosphates | Links inositol signaling to transcription |
| PI3K (human) | Phosphoinositide 3-kinase; inhibited by inositol tetrakisphosphate | Crosstalk with inositol phosphate signaling |
| p110alpha (human) | Catalytic subunit of PI3K; target of inhibition | Involved in cancer cell growth |
| Akt (human) | Downstream effector of PI3K | Modulated by inositol phosphate signaling |
| IPMK (mouse) | Inositol polyphosphate multikinase | Knockout studies reveal roles in development and signaling |
| IPPK (human) | Inositol pentakisphosphate 2-kinase | Produces inositol hexakisphosphate from inositol pentakisphosphate |
| PPIP5K (human) | Diphosphoinositol pentakisphosphate kinase | Generates inositol pyrophosphates from inositol pentakisphosphate |
| PLC (human) | Phospholipase C; produces inositol trisphosphate | Upstream of inositol phosphate pool |
| ITPK1 (human) | Inositol-tetrakisphosphate 1-kinase | Can phosphorylate inositol tetrakisphosphate at different position |
| IPMK (Drosophila) | Inositol polyphosphate multikinase | Genetic model for inositol signaling |
| IpmK (Schizosaccharomyces pombe) | Inositol polyphosphate multikinase | Model for stress response and transcription |
| AtIPK1 (Arabidopsis) | Inositol polyphosphate 6-/3-kinase | Nuclear localization and transcription complementation |
| IP3KA (human) | Inositol 1,4,5-trisphosphate 3-kinase A | Distinct from tetrakisphosphate 3-kinase; calcium signaling |
How Is inositol-1,4,5,6-tetrakisphosphate 3-kinase activity Regulated?
The activity of inositol-1,4,5,6-tetrakisphosphate 3-kinase is regulated at multiple levels. Inositol polyphosphate multikinase (IpmK) controls the levels of its substrate, inositol 1,4,5,6-tetrakisphosphate, and its product, inositol pentakisphosphate. This regulation is critical for maintaining inositol phosphate homeostasis. Additionally, the enzyme can be regulated by cellular localization; in yeast and plants, the kinase is found in the nucleus, where it participates in transcriptional control through the ArgR-Mcm1 complex. Phosphoinositide 3-kinase signaling can also influence the pathway, as inositol 1,4,5,6-tetrakisphosphate inhibits PI3K signaling in human intestinal epithelial cells. Pharmacological inhibition of PI3K with novel antagonists has been shown to inhibit cell growth and tumorigenicity, suggesting crosstalk between inositol phosphate kinases and growth factor signaling.
inositol-1,4,5,6-tetrakisphosphate 3-kinase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| IPMK | Cancer cell growth and tumorigenicity | Knockout in human cancer cell lines (e.g., HCT116) |
| IPMK | Host-pathogen interaction (Salmonella) | Intestinal epithelial cell infection model |
| AtIPK2 | Plant development and stress response | Arabidopsis knockout and complementation |
| IpmK (yeast) | Transcriptional regulation defects | Yeast mutants lacking ArgR-Mcm1 complex |
| PI3K | Cancer and growth factor signaling | Pharmacological inhibition in cancer cell lines |
Cancer and Cell Growth
Dysregulation of inositol polyphosphate signaling has been linked to cancer. Novel functional PI 3-kinase antagonists that inhibit cell growth and tumorigenicity in human cancer cell lines highlight the importance of this pathway. Inositol 1,4,5,6-tetrakisphosphate, the substrate of GO:0000824, can inhibit phosphoinositide 3-kinase signaling pathways, which are frequently hyperactivated in cancer. Therefore, modulating the activity of this kinase could affect cancer cell proliferation and survival.
Infectious Disease and Host-Pathogen Interactions
In human intestinal epithelial cells, inositol 1,4,5,6-tetrakisphosphate is produced in response to Salmonella invasion and inhibits phosphoinositide 3-kinase signaling pathways. This suggests that the 3-kinase activity that consumes this substrate may modulate host defense and bacterial pathogenesis. Understanding how this activity is regulated during infection could provide insights into new therapeutic strategies.
Neurological and Developmental Disorders
Inositol polyphosphates are critical for nuclear signaling and transcriptional control, processes essential for normal development and neuronal function. While direct links to specific neurological diseases are not yet established in the provided literature, the conserved role of this activity in transcription suggests that mutations could contribute to developmental disorders. Further research using model organisms is needed.
From inositol-1,4,5,6-tetrakisphosphate 3-kinase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of IPMK affect inositol phosphate levels? | IPMK knockout cell line (e.g., HEK293) |
| Does the 3-kinase activity require a specific catalytic residue? | Point mutation of predicted active-site aspartate in IPMK |
| Can a tagged IPMK be used to study localization? | Knock-in of FLAG- or GFP-tagged IPMK at endogenous locus |
| Does overexpression of IPMK alter cell growth? | Overexpression of IPMK in cancer cell lines |
| Is the activity conserved in plants? | Arabidopsis AtIPK2 knockout complemented with yeast IpmK |
| Does the product regulate transcription? | Yeast reporter assays with ArgR-Mcm1 complex |
How to Study the inositol-1,4,5,6-tetrakisphosphate 3-kinase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| In vitro kinase assay | Enzymatic conversion of substrate to product | Measuring specific activity of IPMK |
| HPLC separation | Inositol phosphate species | Purification and quantification of reaction products |
| Mass spectrometry | Levels of inositol phosphates in cells | Knockout vs wild-type comparison |
| Complementation assay | Functional rescue of yeast mutants | Testing plant or human orthologs |
| Transcriptional reporter | Activity of ArgR-Mcm1 complex | Linking inositol phosphates to transcription |
| RNA-seq | Global gene expression changes | Downstream effects of IPMK knockout |
| CRISPR knockout | Loss of gene function | Studying IPMK in cancer cell lines |
| Overexpression | Gain of function | Testing oncogenic potential of IPMK |
Enzymatic Assays for 3-Kinase Activity
To directly measure inositol-1,4,5,6-tetrakisphosphate 3-kinase activity, researchers use in vitro kinase assays with radiolabeled ATP and substrate. The reaction products can be separated by HPLC or thin-layer chromatography and quantified. Such assays were used to distinguish this activity from inositol 1,4,5-trisphosphate 3-kinase in rat liver.
Genetic Knockout and Complementation
Knockout of IPMK in yeast or mammalian cells followed by measurement of inositol phosphates by mass spectrometry can reveal the role of this activity in cellular processes. Complementation of yeast mutants with plant or human orthologs can demonstrate functional conservation.
Transcriptional Reporter Assays
Because the product of this activity influences transcription, reporter assays using the ArgR-Mcm1 complex or other inositol-sensitive promoters can be used to study downstream effects. These assays help link enzymatic activity to gene expression changes.
Mass Spectrometry of Inositol Phosphates
Advanced mass spectrometry techniques allow quantification of inositol phosphate species, including inositol 1,4,5,6-tetrakisphosphate and inositol pentakisphosphate, in cell extracts. This method is essential for understanding how modulation of the 3-kinase activity affects the entire inositol phosphate pool.
How CRISPR Can Be Used to Study GO:0000824 inositol-1,4,5,6-tetrakisphosphate 3-kinase activity
Knockout
CRISPR knockout of IPMK or other genes encoding this activity can be used to eliminate the enzyme and study the consequences on inositol phosphate levels, transcription, and cell growth. For example, knockout of IPMK in human cell lines can reveal its role in regulating inositol 1,4,5,6-tetrakisphosphate and downstream signaling.
Point Mutation
Point mutations can be introduced into the catalytic domain of IPMK to abolish kinase activity while preserving protein structure. This allows researchers to distinguish between catalytic and non-catalytic functions of the enzyme. For instance, mutation of the predicted ATP-binding lysine or catalytic aspartate can be tested in kinase assays.
Knock-in
Knock-in of epitope tags (e.g., FLAG, HA, GFP) at the endogenous IPMK locus enables studies of protein localization, interaction, and dynamics. This is particularly useful for nuclear localization studies, as the enzyme is known to function in the nucleus.
Overexpression
Overexpression of wild-type or mutant IPMK can be used to assess gain-of-function effects on cell growth, tumorigenicity, and inositol phosphate metabolism. Overexpression in cancer cell lines may mimic the dysregulation observed in tumors.
How EDITGENE Supports inositol-1,4,5,6-tetrakisphosphate 3-kinase activity Research
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Frequently Asked Questions About inositol-1,4,5,6-tetrakisphosphate 3-kinase activity
What is inositol-1,4,5,6-tetrakisphosphate 3-kinase activity?
It is an enzymatic activity (GO:0000824) that phosphorylates 1D-myo-inositol 1,4,5,6-tetrakisphosphate to form 1D-myo-inositol 1,3,4,5,6-pentakisphosphate, using ATP.
What genes are involved in inositol-1,4,5,6-tetrakisphosphate 3-kinase activity?
Key genes include IPMK (inositol polyphosphate multikinase) in humans and yeast, and AtIPK2 in Arabidopsis.
How is this activity different from inositol 1,4,5-trisphosphate 3-kinase?
The 3-kinase for inositol 1,4,5,6-tetrakisphosphate is biochemically distinct from inositol 1,4,5-trisphosphate 3-kinase, as shown in rat liver.
What is the product of this enzyme?
The product is 1D-myo-inositol 1,3,4,5,6-pentakisphosphate, which can be further phosphorylated to inositol pyrophosphates.
Why is this activity important in cancer?
Inositol polyphosphate signaling, including this activity, can influence cell growth and tumorigenicity; PI3K antagonists inhibit cancer cell growth.
Does this activity play a role in infection?
Yes, inositol 1,4,5,6-tetrakisphosphate produced during Salmonella invasion inhibits PI3K signaling in intestinal epithelial cells.
Is this enzyme found in the nucleus?
Yes, in yeast and plants, inositol polyphosphate kinases are nuclear proteins involved in transcriptional control.
What methods are used to study this activity?
In vitro kinase assays, mass spectrometry, genetic knockout, and transcriptional reporter assays are commonly used.
Can CRISPR be used to study this activity?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are powerful tools to dissect the function of IPMK and related genes.
What diseases are linked to this activity?
Cancer and infectious diseases have been linked to dysregulation of inositol phosphate signaling.
Conclusion
Inositol-1,4,5,6-tetrakisphosphate 3-kinase activity (GO:0000824) is a critical enzymatic step in inositol phosphate metabolism, generating inositol pentakisphosphate, a precursor for higher inositol pyrophosphates and a regulator of nuclear signaling and transcription. Its roles in cancer, infection, and development make it an attractive target for further research. Understanding its mechanism, regulation, and disease connections requires robust experimental models, and CRISPR-based approaches offer powerful tools to investigate this activity in various biological contexts.
References
- 1. Stephens LR et al.. 1988. L-myo-inositol 1,4,5,6-tetrakisphosphate (3-hydroxy)kinase.. Biochem J 249(1):283-92 PMID: 2829850
- 2. Eckmann L et al.. 1997. D-myo-Inositol 1,4,5,6-tetrakisphosphate produced in human intestinal epithelial cells in response to Salmonella invasion inhibits phosphoinositide 3-kinase signaling pathways.. Proc Natl Acad Sci U S A 94(26):14456-60 PMID: 9405634
- 3. Craxton A et al.. 1994. Inositol 1,4,5,6-tetrakisphosphate is phosphorylated in rat liver by a 3-kinase that is distinct from inositol 1,4,5-trisphosphate 3-kinase.. J Biol Chem 269(6):4337-42 PMID: 8308002
- 4. Chang SC et al.. 2006. Inositol polyphosphate multikinase regulates inositol 1,4,5,6-tetrakisphosphate.. Biochem Biophys Res Commun 339(1):209-16 PMID: 16293229
- 5. Odom AR et al.. 2000. A role for nuclear inositol 1,4,5-trisphosphate kinase in transcriptional control.. Science 287(5460):2026-9 PMID: 10720331
- 6. Xia HJ et al.. 2003. Arabidopsis inositol polyphosphate 6-/3-kinase is a nuclear protein that complements a yeast mutant lacking a functional ArgR-Mcm1 transcription complex.. Plant Cell 15(2):449-63 PMID: 12566584
- 7. Razzini G et al.. 2000. Novel functional PI 3-kinase antagonists inhibit cell growth and tumorigenicity in human cancer cell lines.. FASEB J 14(9):1179-87 PMID: 10834940
