NOXO1 Protein

NOXO1 Protein

title: NOXO1 Protein
description: NADPH oxidase organizer 1, p47phox homolog, NOX1 activator, [reactive oxygen species](/entities/reactive-oxygen-species) generation
<div class="infobox infobox-protein">
<table>
<tr><th colspan="2">NOXO1 Protein</th></tr>
<tr><td><strong>Symbol</strong></td><td>NOXO1</td></tr>
<tr><td><strong>Full Name</strong></td><td>NADPH Oxidase Organizer 1</td></tr>
<tr><td><strong>Gene</strong></td><td>[NOXO1](/genes/noxo1)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q8NFA2](https://www.uniprot.org/uniprotkb/Q8NFA2)</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>41.1 kDa</td></tr>
<tr><td><strong>Length</strong></td><td>366 amino acids</td></tr>
<tr><td><strong>Subcellular Location</strong></td><td>Cytoplasm, plasma membrane (with NOX1 complex)</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>Inflammatory bowel disease, Cancer, Neuroinflammation</td></tr>
</table>
</div>

Overview

--- is a protein encoded by the [NOXO1](/genes/noxo1) gene that ### NOX1 Complex Organization. This page describes its structure, normal nervous system function, role in neurodegenerative disease, and potential as a therapeutic target.

Structure

NOXO1 (p41nox) is the organizer subunit for the NOX1 NADPH oxidase complex:

...

NOXO1 Protein

title: NOXO1 Protein
description: NADPH oxidase organizer 1, p47phox homolog, NOX1 activator, [reactive oxygen species](/entities/reactive-oxygen-species) generation
<div class="infobox infobox-protein">
<table>
<tr><th colspan="2">NOXO1 Protein</th></tr>
<tr><td><strong>Symbol</strong></td><td>NOXO1</td></tr>
<tr><td><strong>Full Name</strong></td><td>NADPH Oxidase Organizer 1</td></tr>
<tr><td><strong>Gene</strong></td><td>[NOXO1](/genes/noxo1)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q8NFA2](https://www.uniprot.org/uniprotkb/Q8NFA2)</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>41.1 kDa</td></tr>
<tr><td><strong>Length</strong></td><td>366 amino acids</td></tr>
<tr><td><strong>Subcellular Location</strong></td><td>Cytoplasm, plasma membrane (with NOX1 complex)</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>Inflammatory bowel disease, Cancer, Neuroinflammation</td></tr>
</table>
</div>

Overview

--- is a protein encoded by the [NOXO1](/genes/noxo1) gene that ### NOX1 Complex Organization. This page describes its structure, normal nervous system function, role in neurodegenerative disease, and potential as a therapeutic target.

Structure

NOXO1 (p41nox) is the organizer subunit for the NOX1 NADPH oxidase complex:

Domain Architecture

• PX domain (residues 1-140): Phox homology domain, binds phosphoinositides
• SH3 domains (two): Src homology 3 domains for protein-protein interactions
• Proline-rich regions: Mediate binding to NOXA1
• PB1 domain: Similar to p47phox but constitutively active

Comparison to p47phox

NOXO1 is the homolog of [p47phox](/proteins/ncf1) but with key differences:

• Lacks the autoinhibitory region present in p47phox
• Constitutively membrane-associated
• Does not require phosphorylation for activation

Normal Function

NOX1 Complex Organization

NOXO1 is essential for NOX1 NADPH oxidase assembly:

Membrane recruitment: PX domain binds plasma membrane phosphoinositides

NOX1 interaction: Bridges cytosolic components to membrane-bound NOX1

NOXA1 binding: SH3 domains interact with NOXA1 proline-rich regions

Complex stabilization: Maintains assembled NOX1 complex at membrane

ROS Generation

• Organizes NOX1 complex for superoxide (O2•−) production
• Important for epithelial cell antimicrobial defense
• Contributes to cellular signaling via redox mechanisms

Tissue Expression

• High expression in colon epithelium
• Present in vascular smooth muscle
• Lower levels in brain and other tissues

Role in Neurodegeneration

Neuroinflammation

NOXO1 contributes to neurodegenerative processes through ROS:

Microglial activation: NOX1/NOXO1 complex in activated [microglia](/cell-types/microglia-neuroinflammation)

ROS-mediated damage: Superoxide production damages [neurons](/entities/neurons)

BBB dysfunction: ROS from NOX1 contributes to barrier breakdown

Inflammatory amplification: ROS activates [NF-κB](/entities/nf-kb) signaling

Alzheimer's Disease

• [Aβ](/proteins/amyloid-beta)-induced activation: Aβ peptides may activate NOX1 complex
• Oxidative stress: NOXO1/NOX1 contributes to AD oxidative damage
• [Tau](/proteins/tau) phosphorylation: ROS from NOX1 affects kinase/phosphatase balance

Parkinson's Disease

• Dopaminergic vulnerability: ROS from NOX1 may damage dopaminergic neurons
• [α-synuclein](/proteins/alpha-synuclein) effects: Aggregated α-synuclein may activate NOX complexes
• Neuroinflammation: Contributes to microglial ROS production

Vascular Cognitive Impairment

• Vascular ROS: NOX1/NOXO1 in cerebral vessels
• Endothelial dysfunction: Contributes to vascular dysfunction
• [Blood-brain barrier](/entities/blood-brain-barrier): ROS disrupts tight junctions

Molecular Mechanisms

NOX1 Complex Assembly

| Component | Role | Interaction |
|-----------|------|-------------|
| NOX1 | Catalytic subunit | Membrane-bound flavocytochrome |
| NOXO1 | Organizer | Bridges NOXA1 to NOX1 |
| NOXA1 | Activator | Provides FAD binding site |
| p22phox | Stabilizer | Membrane anchor for NOX1 |

PX Domain Function

• Binds PI(3)P, PI(3,4)P2, and PI(4,5)P2
• Constitutive membrane localization
• Different lipid specificity than p47phox

Regulation

Unlike p47phox, NOXO1 does not require:

• Protein kinase C phosphorylation
• WASP/SCAR proteins for activation
• Conformational change for membrane binding

Therapeutic Targeting

NOX1-Specific Inhibitors

• ML171: NOX1-selective inhibitor (also affects NOX2)
• Compound development: Ongoing efforts for NOX1-specific inhibitors

Broader NOX Inhibition

• Apocynin: Pan-NOX inhibitor (natural compound)
• VAS2870: NOX2/4 inhibitor with some NOX1 activity
• GKT137831 (Setanaxib): NOX1/4 dual inhibitor in clinical trials

Neuroprotective Potential

• Targeting NOXO1-NOXA1 interaction
• Disrupting PX domain membrane binding
• Reducing NOX1-mediated neuroinflammation

Key Interactions

| Interacting Protein | Function | Disease Relevance |
|-------------------|----------|-------------------|
| NOX1 | Catalytic partner | ROS generation |
| NOXA1 | Activator subunit | Complex assembly |
| p22phox | Membrane anchor | Complex stability |
| PI(3)P | Membrane lipid | Membrane targeting |

See Also

• [NOXO1 Gene](/genes/noxo1)
• [NOXA1](/proteins/noxa1)
• [NOX2/CYBB](/proteins/nox2)
• [Oxidative Stress](/mechanisms/oxidative-stress)
• [Neuroinflammation](/mechanisms/neuroinflammation)

External Links

• [UniProt: Q8NFA2](https://www.uniprot.org/uniprotkb/Q8NFA2)
• [NCBI Gene: 124628](https://www.ncbi.nlm.nih.gov/gene/124628)

References

[Banfi et al., NOXO1 and NOXA1 are NOX1 activators (2003) (2003)](https://doi.org/10.1016/j.molcel.2003.08.003)

[Cheng et al., NOXO1 structure and function (2006) (2006)](https://doi.org/10.1074/jbc.M603320200)

[Unknown, Bedard and Krause, NOX enzymes in health and disease (2007) (2007)](https://doi.org/10.1152/physrev.00044.2005)

[Unknown, Sorce and Krause, NOX enzymes in the CNS (2009) (2009)](https://doi.org/10.1016/j.freeradbiomed.2009.01.016)

[Cifuentes-Pagano et al., NOX inhibitors (2014) (2014)](https://doi.org/10.1152/ajpheart.00044.2014)

[Altenhöfer et al., NOX1 in disease (2015) (2015)](https://doi.org/10.1007/s00109-015-1273-7)

[Wingler et al., NOXO1 in NOX1 activation (2016) (2016)](https://doi.org/10.1016/j.freeradbiomed.2016.01.014)

[Crestani et al., NOX enzymes in neurodegeneration (2021) (2021)](https://doi.org/10.1016/j.nbd.2021.105345)

[Drummond et al., NOX family targeting in disease (2022) (2022)](https://doi.org/10.1038/s41573-022-00536-0)

[Ma et al., NOX1 in brain disorders (2022) (2022)](https://doi.org/10.3389/fncel.2022.876371)