PI3K Protein

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PI3K Protein

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">PI3K Protein</th>
</tr>
<tr>
<td class="label">Gene</td>
<td>[PIK3CA](/genes/PIK3CA) (p110α), [PIK3CB](/genes/PIK3CB) (p110β)</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P42336" target="_blank">P42336</a> (p110α)</td>
</tr>
<tr>
<td class="label">PDB</td>
<td><a href="https://www.rcsb.org/structure/4OVU" target="_blank">4OVU</a>, <a href="https://www.rcsb.org/structure/3ZMS" target="_blank">3ZMS</a></td>
</tr>
<tr>
<td class="label">Mol. Weight</td>
<td>110 kDa (catalytic subunit)</td>
</tr>
<tr>
<td class="label">Localization</td>
<td>Plasma membrane, cytoplasm</td>
</tr>
<tr>
<td class="label">Family</td>
<td>PI3K family, lipid kinases</td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>[Alzheimer's Disease](/diseases/alzheimers), [Parkinson's Disease](/diseases/parkinsons-disease), [Cancer](/diseases/cancer)</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/ad" style="color:#ef9a9a">AD</a>, <a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">ALZHEIMER</a>, <a href="/wiki/alzheimer's-disease" style="color:#ef9a9a">ALZHEIMER'S DISEASE</a>, <a href="/wiki/ami" style="color:#ef9a9a">AMI</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">3507 edges</a></td>
</tr>
</table>

...

PI3K Protein

Introduction

Pi3K Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

PI3K (Phosphoinositide 3-kinase) is a key signaling enzyme that generates phosphatidylinositol (3,4,5)-trisphosphate (PIP3), a critical second messenger that regulates cell survival, growth, proliferation, and metabolism[@cantley2002]. In [neurons](/entities/neurons), PI3K signaling is essential for development, synaptic plasticity, and neuroprotection against various stresses[@th2019].

There are multiple PI3K classes, with Class I PI3Ks being most relevant to signaling:

Class IA: p110α (PIK3CA), p110β (PIK3CB), p110δ (PIK3CD)
Class IB: p110γ (PIK3CG)

Each has distinct cellular functions and expression patterns[@zhang2017].

Structure

Class I PI3Ks have a characteristic structure:

Adapter Subunit (p85)

The regulatory subunit contains:

Two SH2 domains for receptor binding
SH3 domain for protein interactions
Inter-SH2 (iSH2) domain for p110 binding

Catalytic Subunit (p110)

The catalytic subunit contains:

Kinase domain
C2 domain for membrane association
Ras-binding domain (RBD)
Helical domain

Membrane Targeting

PI3K is recruited to the membrane via:

SH2 domain binding to phosphotyrosines
Direct binding to activated receptors
Membrane PIP2 substrate availability[@liu2020]

Normal Function

Signal Transduction

PI3K is activated by:

Receptor tyrosine kinase activation
G protein-coupled receptors
Small GTPases (Ras)
Integrin signaling

Key Pathways

PI3K activates multiple downstream effectors:

Akt/PKB: Cell survival, metabolism
PDK1: Activates Akt
[mTOR](/mechanisms/mtor-signaling-pathway): Growth, protein synthesis
GSK-3: Multiple cellular functions

Neuronal Functions

In neurons, PI3K regulates:

Neurotrophin signaling (Trk receptors)
Synaptic plasticity ([LTP](/mechanisms/long-term-potentiation), LTD)
Neuronal survival
Dendritic spine morphology[^5]

Role in Disease

Alzheimer's Disease

PI3K/Akt signaling is implicated in AD:

Neurotrophin signaling deficits
[Tau](/proteins/tau) phosphorylation dysregulation
[Amyloid-beta](/proteins/amyloid-beta) affects PI3K pathway
Therapeutic targeting potential

Parkinson's Disease

In PD:

PI3K protects dopaminergic neurons
LRRK2 affects PI3K signaling
Neurotrophin (GDNF) signaling requires PI3K
PINK1/Parkin pathway connections

Cancer

PI3K is frequently mutated/activated:

PIK3CA mutations in many cancers
Oncogenic signaling drives proliferation
Therapeutic target (PI3K inhibitors)[^6]

Therapeutic Targeting

Therapeutic strategies include:

PI3K inhibitors: Cancer therapy (idelalisib, alpelisib)
PI3K activators: Neuroprotective approaches
Akt activators: Downstream neuroprotection
mTOR inhibitors: Modulate downstream signaling
Combined approaches: PI3K + other therapies[^7]

Background

The study of Pi3K Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

Pathway & Interaction Diagram

Interactive diagram showing PI3K's key relationships in the SciDEX knowledge graph (15 connections shown).

Mermaid diagram (expand to render)

References

External Links

[UniProt:-- [Gene: PIK3CA (NCBI)](https://www.ncbi.nlm.nih.gov/gene/5290)

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PI3K Protein

PI3K Protein

PI3K Protein

PI3K Protein

Introduction

Overview

Structure

Adapter Subunit (p85)

Catalytic Subunit (p110)

Membrane Targeting

Normal Function

Signal Transduction

Key Pathways

Neuronal Functions

Role in Disease

Alzheimer's Disease

Parkinson's Disease

Cancer

Therapeutic Targeting

Background

Pathway & Interaction Diagram

See Also

References

External Links