GO:0035014 phosphatidylinositol 3-kinase regulator activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0035014 phosphatidylinositol 3-kinase regulator activity describes proteins that modulate the activity of phosphatidylinositol 3-kinase (PI3K), often by linking catalytic subunits to upstream signals and positioning them near lipid substrates.
• Regulatory subunits such as PIK3R1 (p85alpha) are classic examples of PI3K regulators that control class I PI3K catalytic activity.
• PI3K regulator activity is central to insulin signaling, growth factor responses, autophagy initiation, and immune signaling.
• Dysregulation of PI3K regulators contributes to cancer, metabolic disorders, and viral infection outcomes.
• CRISPR knockout, point mutation, knock-in, and overexpression models are essential to dissect how PI3K regulators control downstream AKT signaling.
• Studying GO:0035014 requires combining biochemical assays, phosphoinositide profiling, and genetic screens to link regulator function to cellular phenotypes.
Description
Phosphatidylinositol 3-kinase (PI3K) regulator activity, GO:0035014, is a molecular function that modulates the activity of PI3K enzymes. PI3K signaling is one of the most frequently altered pathways in human disease, and regulatory subunits are critical for linking upstream receptor signals to catalytic activation. Understanding this activity helps researchers interpret how cells convert extracellular cues into lipid second messengers and downstream kinase cascades. The term is defined in QuickGO as modulating the activity of a PI3K, where regulatory subunits can link a PI3K catalytic subunit to upstream signaling events and help position the catalytic subunits close to their lipid substrates. This function is distinct from the catalytic activity itself and is essential for spatial and temporal control of PI3K signaling. In this article, we synthesize authoritative GO annotations and verified PubMed literature to explain the mechanism, key genes, disease relevance, and research methods for GO:0035014.
phosphatidylinositol 3-kinase regulator activity At A Glance
| GO ID | GO:0035014 |
|---|---|
| GO term | phosphatidylinositol 3-kinase regulator activity |
| Ontology | molecular_function |
| Synonym | phosphoinositide 3-kinase regulator activity; PI3K regulator activity |
| Major function | Modulates PI3K activity by linking catalytic subunits to upstream signals and positioning them near lipid substrates |
| Related catalytic activity | Phosphatidylinositol 3-kinase activity (catalytic subunit) |
| Example regulators | PIK3R1 (p85alpha), PIK3R2, PIK3R3, PIK3R4, PIK3R5, PIK3R6 |
| Pathway context | PI3K/AKT signaling, insulin signaling, autophagy initiation, immune receptor signaling |
| Disease relevance | Cancer, metabolic disorders, viral infection, neurodegeneration |
What Is GO:0035014?
GO:0035014 phosphatidylinositol 3-kinase regulator activity is a molecular function in which a protein modulates the activity of a phosphatidylinositol 3-kinase (PI3K). Regulatory subunits can link a PI3K catalytic subunit to upstream signaling events and help position the catalytic subunits close to their lipid substrates. This activity is also known as phosphoinositide 3-kinase regulator activity or PI3K regulator activity.
Why Is phosphatidylinositol 3-kinase regulator activity Important in Cell Biology?
PI3K regulator activity is important because it determines when, where, and how strongly PI3K signaling is activated. The PI3K/AKT pathway controls cell growth, survival, metabolism, and autophagy, and regulatory subunits are the key nodes that integrate upstream inputs from receptor tyrosine kinases, G-protein-coupled receptors, and insulin receptors. Without proper regulation, PI3K signaling can become constitutive, driving tumorigenesis and metabolic disease. Moreover, PI3K regulators are involved in host responses to viral infection and in skeletal muscle homeostasis, making them attractive targets for therapeutic intervention.
• Controls spatial and temporal activation of PI3K, a central node in growth factor and insulin signaling.
• Regulates AKT phosphorylation and downstream effects on cell survival, proliferation, and metabolism.
• Participates in autophagy initiation through class III PI3K complexes.
• Modulates skeletal muscle protein turnover and mitochondrial biogenesis.
• Influences immune signaling and responses to negative-stranded RNA viruses.
• Dysregulation is linked to cancer, diabetes, and muscle atrophy.
• Provides a mechanism for cross-talk between AMPK and PI3K/AKT pathways.
• Essential for corneal epithelium homeostasis and wound healing.
• Target of natural compounds such as berberine and 5,7-dimethoxyflavone.
• Enables precise experimental dissection using CRISPR-based genetic models.
What Happens During phosphatidylinositol 3-kinase regulator activity?
Upstream signal recognition and recruitment
In simple terms: First, the regulator helps the PI3K enzyme hear the signal from outside the cell.
Regulatory subunits of PI3K contain domains that recognize activated receptor tyrosine kinases or adaptor proteins. For example, the p85 regulatory subunit of class I PI3K binds to phosphotyrosine motifs on activated receptors, recruiting the catalytic subunit to the membrane. This step is critical for linking upstream signaling events to PI3K activation.
Membrane localization and substrate positioning
In simple terms: The regulator moves the PI3K enzyme next to its lipid targets in the membrane.
Once recruited, the regulatory subunit helps position the catalytic subunit close to its lipid substrates, phosphatidylinositol 4,5-bisphosphate (PIP2) and related phosphoinositides, in the plasma membrane or endosomal membranes. This positioning ensures efficient conversion of PIP2 to PIP3, a key second messenger.
Catalytic activation and PIP3 production
In simple terms: The PI3K enzyme then produces a lipid signal called PIP3.
Upon proper positioning, the catalytic subunit phosphorylates PIP2 to generate PIP3. PIP3 recruits downstream effectors such as AKT and PDK1, leading to AKT phosphorylation and activation of survival, growth, and metabolic programs. Regulatory subunits modulate the magnitude and duration of this response.
Feedback regulation and signal termination
In simple terms: The regulator also helps shut the signal off when it is no longer needed.
PI3K signaling is terminated by lipid phosphatases such as PTEN, which converts PIP3 back to PIP2. Regulatory subunits can also be modified by phosphorylation or ubiquitination to attenuate PI3K activity. This feedback prevents excessive signaling that could lead to disease.
Integration with autophagy and class III PI3K complexes
In simple terms: Regulators also work in autophagy, a cellular recycling process.
Class III PI3K complexes, which include regulatory subunits such as VPS34 and Beclin-1, are essential for autophagy initiation. The regulatory subunits in these complexes help localize the catalytic activity to autophagosome formation sites and coordinate with upstream nutrient-sensing pathways.
Key Genes Involved in GO:0035014 phosphatidylinositol 3-kinase regulator activity
The following genes encode proteins with phosphatidylinositol 3-kinase regulator activity or are directly involved in its regulation.
| Gene | Major Role | Research Relevance |
|---|---|---|
| PIK3R1 | Encodes p85alpha, the canonical regulatory subunit of class IA PI3K | Most frequently mutated PI3K regulator in cancer and metabolic disease |
| PIK3R2 | Encodes p85beta, a regulatory subunit with tissue-specific functions | Implicated in insulin signaling and cancer |
| PIK3R3 | Encodes p55gamma, a regulatory subunit that modulates PI3K activity | Studied in cancer and neuronal signaling |
| PIK3R4 | Encodes VPS15, a regulatory subunit of class III PI3K | Essential for autophagy initiation and endosomal trafficking |
| PIK3R5 | Encodes p101, a regulatory subunit for class IB PI3K | Links G-protein-coupled receptors to PI3Kgamma |
| PIK3R6 | Encodes p84, a regulatory subunit for class IB PI3K | Modulates immune cell signaling |
| PIK3CA | Encodes the catalytic subunit p110alpha of class IA PI3K | Oncogene; its activity is regulated by PIK3R1 |
| PIK3CB | Encodes the catalytic subunit p110beta | Regulated by p85 subunits; involved in insulin signaling |
| PIK3CD | Encodes the catalytic subunit p110delta | Regulated by p85 subunits; important in immune cells |
| PIK3CG | Encodes the catalytic subunit p110gamma | Regulated by p101/p84; involved in inflammation |
| PTEN | Lipid phosphatase that opposes PI3K by converting PIP3 to PIP2 | Tumor suppressor; loss increases PI3K signaling |
| AKT1 | Downstream effector kinase activated by PIP3 | Readout of PI3K regulator activity |
| MTOR | Kinase in mTORC1 and mTORC2 complexes downstream of PI3K/AKT | Integrates growth and nutrient signals |
| BECN1 | Beclin-1, part of class III PI3K complex in autophagy | Regulated by PI3K regulators during autophagy |
| IRS1 | Insulin receptor substrate 1, adaptor that recruits PI3K regulators | Key node in insulin signaling |
| IGF1R | Insulin-like growth factor 1 receptor, upstream activator of PI3K | Regulates PI3K via adaptor proteins |
| AMPK | Energy sensor that cross-talks with PI3K/AKT pathway | Modulates PI3K regulator activity under metabolic stress |
How Is phosphatidylinositol 3-kinase regulator activity Regulated?
Phosphatidylinositol 3-kinase regulator activity is itself regulated at multiple levels. Upstream signals from receptor tyrosine kinases and G-protein-coupled receptors recruit regulatory subunits to the membrane, while phosphorylation of regulatory subunits can alter their binding affinities. The AMPK pathway can inhibit PI3K/AKT signaling under energy stress, providing cross-talk between metabolic and growth signals. In autophagy, class III PI3K regulators are controlled by nutrient-sensing kinases such as mTORC1. Additionally, negative feedback loops involving PTEN and lipid phosphatases terminate PI3K signals.
phosphatidylinositol 3-kinase regulator activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PIK3R1 | Cancer, insulin resistance | Knockout and point-mutation cell lines; xenograft models |
| PIK3R4 | Autophagy-related neurodegeneration | Knockout cells with autophagy flux assays |
| PTEN | Cancer predisposition | Knockout and overexpression models |
| IRS1 | Type 2 diabetes | Knockout and knock-in models in muscle cells |
| AKT1 | Cancer, growth disorders | Point-mutation knock-in for constitutive activation |
Cancer
Mutations in PIK3R1 and other PI3K regulatory subunits are found in cancers, leading to constitutive PI3K/AKT activation that promotes tumor growth and survival. Loss of PTEN further amplifies this signaling. Targeting PI3K regulators is a major therapeutic strategy.
Metabolic disorders and muscle atrophy
PI3K regulator activity is essential for insulin signaling and skeletal muscle homeostasis. Dysregulation contributes to insulin resistance, diabetes, and muscle atrophy, as shown in models of myocardial infarction and sarcopenia.
Viral infection and immune response
PI3K/AKT signaling modulated by regulatory subunits influences host responses to negative-stranded RNA viruses, affecting viral replication and interferon responses.
Neurodegeneration and autophagy dysfunction
Class III PI3K regulators are critical for autophagy, and their dysfunction is linked to neurodegenerative diseases where autophagic clearance is impaired.
From phosphatidylinositol 3-kinase regulator activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of PIK3R1 affect AKT phosphorylation? | PIK3R1 knockout cell line |
| Does a specific point mutation in PIK3R1 alter PI3K binding? | Point-mutation knock-in cell line |
| How does tagged PIK3R1 localize during signaling? | Tagged knock-in with fluorescent protein |
| Does overexpression of PIK3R2 increase PIP3 levels? | Overexpression cell line |
| Which genes modulate PI3K regulator activity? | CRISPR library screening |
| How does PIK3R4 loss affect autophagy? | Knockout cells with LC3 flux assays |
How to Study the phosphatidylinositol 3-kinase regulator activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| In vitro PI3K assay | Catalytic conversion of PIP2 to PIP3 | Measure regulator effect on PI3K activity |
| Lipidomics (LC-MS) | Levels of phosphoinositides | Quantify PIP3 in knockout cells |
| Western blot for pAKT | AKT phosphorylation at Ser473/Thr308 | Readout of PI3K pathway activation |
| CRISPR knockout screen | Gene essentiality and pathway modifiers | Identify novel PI3K regulators |
| Proximity labeling (BioID) | Protein-protein interactions | Map regulator interactome |
| Live-cell imaging | Subcellular localization dynamics | Track regulator recruitment to membrane |
| Autophagy flux assay | LC3 lipidation and degradation | Assess class III PI3K regulator function |
| RNA-seq | Transcriptional changes | Measure downstream gene expression |
Biochemical assays for PI3K activity
In vitro PI3K assays using lipid substrates and radioactive ATP measure catalytic activity in the presence or absence of regulatory subunits. These assays help quantify the modulatory effect of GO:0035014 proteins.
Phosphoinositide profiling by mass spectrometry
Mass spectrometry-based lipidomics can quantify PIP2 and PIP3 levels in cells with genetic alterations in PI3K regulators, providing direct readouts of pathway activity.
CRISPR screens and functional genomics
Genome-wide CRISPR knockout or activation screens can identify genes that modulate PI3K signaling, revealing novel regulators and their impact on cell fitness.
Imaging and proximity labeling
Fluorescence microscopy and proximity labeling (e.g., BioID) can visualize where PI3K regulators localize and which proteins they interact with during signaling.
How CRISPR Can Be Used to Study GO:0035014 phosphatidylinositol 3-kinase regulator activity
Knockout
CRISPR knockout of PI3K regulator genes such as PIK3R1 or PIK3R4 allows researchers to assess loss-of-function phenotypes, including changes in AKT phosphorylation, PIP3 levels, and autophagy.
Point Mutation
Introducing specific point mutations in regulatory subunits (e.g., in PIK3R1) can mimic cancer-associated variants or disrupt binding interfaces, enabling structure-function studies of GO:0035014.
Knock-in
Knock-in of tagged versions of PI3K regulators (e.g., GFP or HA tags) facilitates localization and interaction studies without altering endogenous expression levels.
Overexpression
Overexpression of wild-type or mutant PI3K regulatory subunits can amplify or disrupt signaling, helping to determine sufficiency and dominant-negative effects.
How EDITGENE Supports phosphatidylinositol 3-kinase regulator activity Research
Researchers studying phosphatidylinositol 3-kinase regulator activity-related genes often need to determine whether a candidate gene is causally involved in PI3K signaling, and CRISPR-based models provide the most direct way to test this.
Contact EDITGENE today to design your custom CRISPR model for phosphatidylinositol 3-kinase regulator activity research.
Frequently Asked Questions About phosphatidylinositol 3-kinase regulator activity
What is phosphatidylinositol 3-kinase regulator activity?
It is a molecular function (GO:0035014) where a protein modulates the activity of PI3K, often by linking catalytic subunits to upstream signals and positioning them near lipid substrates.
What genes are involved in phosphatidylinositol 3-kinase regulator activity?
Key genes include PIK3R1, PIK3R2, PIK3R3, PIK3R4, PIK3R5, and PIK3R6, which encode regulatory subunits of PI3K.
How does PI3K regulator activity affect AKT signaling?
Regulatory subunits control the production of PIP3, which recruits AKT to the membrane for phosphorylation and activation.
What diseases are linked to PI3K regulator activity?
Cancer, insulin resistance, muscle atrophy, and viral infections are associated with dysregulated PI3K regulators.
How can I study phosphatidylinositol 3-kinase regulator activity?
Common methods include CRISPR knockout, point mutation, knock-in, overexpression, lipidomics, and phospho-AKT western blotting.
What is the role of PIK3R1 in PI3K regulation?
PIK3R1 encodes p85alpha, which binds activated receptors and recruits the p110 catalytic subunit to the membrane.
Is phosphatidylinositol 3-kinase regulator activity involved in autophagy?
Yes, class III PI3K regulators such as PIK3R4 are essential for autophagy initiation.
What CRISPR models are available for PI3K regulator genes?
Knockout, point mutation, knock-in, and overexpression models can be generated for any PI3K regulator gene.
How does AMPK interact with PI3K regulator activity?
AMPK can inhibit PI3K/AKT signaling under energy stress, providing cross-talk between metabolic and growth pathways.
What is the GO ID for phosphatidylinositol 3-kinase regulator activity?
The GO ID is GO:0035014.
Conclusion
Phosphatidylinositol 3-kinase regulator activity (GO:0035014) is a fundamental molecular function that controls PI3K signaling, impacting cell growth, metabolism, autophagy, and immune responses. Dysregulation of PI3K regulators is implicated in cancer, metabolic disorders, and infections, making them important therapeutic targets. Advances in CRISPR-based models and biochemical assays continue to illuminate the precise mechanisms of these regulators, offering new opportunities for drug discovery and precision medicine.
References
- 1. Chen K et al.. 2022. The role of the PI3K/AKT signalling pathway in the corneal epithelium: recent updates.. Cell Death Dis 13(5):513 PMID: 35641491
- 2. Kim C et al.. 2020. The 5,7-Dimethoxyflavone Suppresses Sarcopenia by Regulating Protein Turnover and Mitochondria Biogenesis-Related Pathways.. Nutrients 12(4) PMID: 32295051
- 3. Thiel G et al.. 2021. Insulin-Responsive Transcription Factors.. Biomolecules 11(12) PMID: 34944530
- 4. Feng L et al.. 2022. Aerobic exercise and resistance exercise alleviate skeletal muscle atrophy through IGF-1/IGF-1R-PI3K/Akt pathway in mice with myocardial infarction.. Am J Physiol Cell Physiol 322(2):C164-C176 PMID: 34852207
- 5. Hurley JH et al.. 2017. Mechanisms of Autophagy Initiation.. Annu Rev Biochem 86:225-244 PMID: 28301741
- 6. Caux M et al.. 2022. Class III PI3K Biology.. Curr Top Microbiol Immunol 436:69-93 PMID: 36243840
- 7. Huang J et al.. 2021. Berberine Exerts Anti-cancer Activity by Modulating Adenosine Monophosphate- Activated Protein Kinase (AMPK) and the Phosphatidylinositol 3-Kinase/ Protein Kinase B (PI3K/AKT) Signaling Pathways.. Curr Pharm Des 27(4):565-574 PMID: 32988344
- 8. Blanco J et al.. 2020. Phosphatidylinositol-3-kinase-Akt pathway in negative-stranded RNA virus infection: a minireview.. Arch Virol 165(10):2165-2176 PMID: 32740830
