QSOX1 Protein

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QSOX1 Protein

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QSOX1 Protein

Introduction

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">QSOX1 Protein</th>
</tr>
<tr>
<td class="label">Name</td>
<td>QSOX1</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Quiescin Q6 Sulfhydryl Oxidase 1</td>
</tr>
<tr>
<td class="label">Gene</td>
<td>QSOX1</td>
</tr>
<tr>
<td class="label">Alternative Names</td>
<td>QSOX, Q6, QSCN6, ERP19</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>Sulfhydryl oxidase, ERV/QUSOX family</td>
</tr>
<tr>
<td class="label">Length</td>
<td>609 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~67 kDa</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td>O00391</td>
</tr>
<tr>
<td class="label">Cellular Compartment</td>
<td>Endoplasmic reticulum (ER) lumen</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/colorectal-cancer" style="color:#ef9a9a">Colorectal Cancer</a>, <a href="/wiki/diabetes" style="color:#ef9a9a">Diabetes</a>, <a href="/wiki/melanoma" style="color:#ef9a9a">Melanoma</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">29 edges</a></td>
</tr>
</table>

...

QSOX1 Protein

Introduction

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">QSOX1 Protein</th>
</tr>
<tr>
<td class="label">Name</td>
<td>QSOX1</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Quiescin Q6 Sulfhydryl Oxidase 1</td>
</tr>
<tr>
<td class="label">Gene</td>
<td>QSOX1</td>
</tr>
<tr>
<td class="label">Alternative Names</td>
<td>QSOX, Q6, QSCN6, ERP19</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>Sulfhydryl oxidase, ERV/QUSOX family</td>
</tr>
<tr>
<td class="label">Length</td>
<td>609 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~67 kDa</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td>O00391</td>
</tr>
<tr>
<td class="label">Cellular Compartment</td>
<td>Endoplasmic reticulum (ER) lumen</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/colorectal-cancer" style="color:#ef9a9a">Colorectal Cancer</a>, <a href="/wiki/diabetes" style="color:#ef9a9a">Diabetes</a>, <a href="/wiki/melanoma" style="color:#ef9a9a">Melanoma</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">29 edges</a></td>
</tr>
</table>

Qsox1 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

QSOX1 (Quiescin Q6 Sulfhydryl Oxidase 1) is an ER-resident enzyme belonging to the quiescin-sulfhydryl oxidase family that catalyzes the formation of disulfide bonds in newly synthesized proteins[@chakravarthi2006][@sevier2008]. This enzyme plays a critical role in protein quality control within the endoplasmic reticulum (ER) and has emerged as a significant protein in neurodegenerative disease research due to its involvement in ER stress responses and protein aggregation mechanisms in Alzheimer's disease (AD), Parkinson's disease (PD), and other disorders[@wang2016][@hotamisligil2010].

Protein Information

Structure

QSOX1 possesses a multi-domain architecture essential for its enzymatic function[@wells2008][@thorpe2002]:

N-terminal signal peptide: Directs protein to the ER lumen (1-20 aa)

Thioredoxin-like domain: Contains CXXC motif for initial thiol oxidation (residues 100-200)

Linker region: Flexible connector between domains

C-terminal sulfhydryl oxidase domain (ERO1-like): Catalytic domain with FAD-binding motif (residues 400-550)

The enzyme contains multiple conserved cysteine residues essential for catalytic activity and substrate recognition[@hoober1999].

Catalytic Mechanism

Overall Reaction

QSOX1 catalyzes disulfide bond formation using molecular oxygen as the electron acceptor[@fass2013][@gross2002]:

Protein-SH + Protein-SH + O₂ → Protein-S-S-Protein + H₂O₂

Catalytic Cycle

Substrate binding: Thiol groups of target proteins bind to the thioredoxin domain

FAD-mediated oxidation: Electrons transferred to FAD cofactor, forming FADH₂

Oxygen reduction: FADH₂ reduces O₂ to H₂O₂

Product release: Disulfide-bonded protein released, H₂O₂ diffuses

Substrate Specificity

QSOX1 can oxidize a broad range of substrates including[@appenzellerherzog2008]:

Thioredoxin
Protein disulfide isomerase (PDI) family members
ERp44
Various growth factors and cytokines
Small secreted proteins

Biological Functions

Protein Quality Control

Ensures proper disulfide bond formation in nascent polypeptides
Participates in ER-associated degradation (ERAD) pathway
Maintains ER redox homeostasis
Prevents accumulation of misfolded proteins

Role in Secretory Pathway

Maturation of secreted proteins
Processing of membrane proteins
Quality control checkpoint for protein folding

Role in Neurodegenerative Diseases

Alzheimer's Disease

QSOX1 is implicated in multiple aspects of AD pathogenesis[@hoober2019][@scheper2015]:

ER stress response: Upregulated during ER stress caused by [amyloid-beta](/proteins/amyloid-beta) and [tau](/proteins/tau) accumulation. The unfolded protein response (UPR) is chronically activated in AD brains[@katayama2004].

Protein quality control: Helps manage misfolded proteins, but overwhelming aggregation can exceed QSOX1 capacity[@kimata2011].

Oxidative stress: Produces H₂O₂ as byproduct; while ER has antioxidant systems, excessive production contributes to oxidative damage in AD[@butterfield2008].

Synaptic proteins: Proper disulfide bond formation is critical for synaptic function; QSOX1 dysfunction may impair synaptic plasticity[@hong2020].

Parkinson's Disease

In PD, QSOX1 involvement includes[@ogawa2020][@lindholm2006]:

[Alpha-synuclein](/proteins/alpha-synuclein) aggregation: QSOX1 helps manage ER stress induced by [alpha-synuclein](/mechanisms/alpha-synuclein) oligomerization

Dopaminergic neuron vulnerability: High metabolic demands make these [neurons](/entities/neurons) particularly sensitive to protein folding defects

Mitochondrial crosstalk: ER stress and mitochondrial dysfunction are interconnected in PD pathogenesis

Other Neurodegenerative Conditions

Amyotrophic Lateral Sclerosis (ALS): QSOX1 expression altered in models of [TDP-43](/proteins/tdp-43) proteinopathy[@pasinelli2006]
Huntington's Disease: May assist in handling mutant [huntingtin](/proteins/huntingtin-protein) protein aggregates[@takahashi2007]
Prion Diseases: Potential role in prion protein quality control[@harris2019]

Therapeutic Implications

QSOX1 represents a promising therapeutic target[@scalcon2020][@kim2008]:

Potential Interventions

QSOX1 activity enhancers: Compounds that boost enzymatic function could improve protein folding capacity

Antioxidant approaches: Targeting downstream effects of QSOX1-mediated H₂O₂ production

ER stress modulators: General ER stress alleviators may be beneficial

Protein folding chaperones: Adjunctive therapies to support QSOX1 function

Research Status

Preclinical studies are exploring QSOX1 modulators in cellular and animal models. No clinical trials for QSOX1-targeted neurodegenerative therapies exist as of 2024.

Interactions

Protein Partners

PDI (Protein Disulfide Isomerase): Key partner in ER protein folding
ERp44: ER quality control protein
ERdj3/5/8: ER chaperones in UPR signaling
BiP/GRP78: Major ER chaperone
Calnexin/Calreticulin: ER folding assistants

Pathway Involvement

[Unfolded Protein Response](/entities/unfolded-protein-response) (UPR)
ER-Associated Degradation (ERAD)
Oxidative protein folding pathway
Protein disulfide isomerase system
[Autophagy](/entities/autophagy)-lysosomal pathway

Background

The study of Qsox1 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.

Cross-References

[QSOX1 Gene](/proteins/qsox1-protein)
[Protein Quality Control](/mechanisms/protein-quality-control-network)mechanisms/protein-quality-control-network)
[Unfolded Protein Response](/mechanisms/endoplasmic-reticulum-stress)mechanisms/er-stress-unfolded-protein-response)
[ER Stress in Neurodegeneration](/mechanisms/er-stress-neurodegeneration)
[Oxidative Stress in AD](/mechanisms/oxidative-stress-alzheimers)
[Oxidative Stress in PD](/mechanisms/oxidative-stress-parkinsons)
[Alpha-Synuclein Pathology](/mechanisms/alpha-synuclein-pathology)
[Amyloid Cascade](/mechanisms/amyloid-cascade)
[Tau Pathology](/mechanisms/tau-pathology)
[Synaptic Dysfunction](/mechanisms/synaptic-dysfunction)
[ER-Associated Degradation](/mechanisms/erad-pathway)

External Links

[UniProt: QSOX1](https://www.uniprot.org/uniprot/O00391)
[NCBI Protein: QSOX1](https://www.ncbi.nlm.nih.gov/protein/NP_001027551)
[PDB: QSOX1 Structure](https://www.ebi.ac.uk/pdbe/entry/pdb/2VX3)
[Human Protein Atlas: QSOX1](https://www.proteinatlas.org/ENSG00000116236-QSOX1)
[OMIM: QSOX1](https://www.omim.org/entry/603180)

References

[Chakravarthi S, Jessop CE, Bulleid NJ, The role of glutathione in disulphide bond formation and endoplasmic reticulum-oxidoreductin-1 (Ero1)-mediated oxidative protein folding (2006)](https://pubmed.ncbi.nlm.nih.gov/17052205/)

[Sevier CS, Kaiser CA, Ero1 and the role of disulfide bond formation in the endoplasmic reticulum (2008)](https://pubmed.ncbi.nlm.nih.gov/18850258/)

[Wang M, Kaufman RJ, The impact of protein-misfolding and ER stress on neurodegenerative diseases (2016)](https://pubmed.ncbi.nlm.nih.gov/27857110/)

[Hotamisligil GS, Endoplasmic reticulum stress and the inflammatory basis of metabolic disease (2010)](https://pubmed.ncbi.nlm.nih.gov/20303879/)

[Wells M, Miao R, Wang J, et al, Structure and function of human QSOX1 (2008)](https://pubmed.ncbi.nlm.nih.gov/18775691/)

[Thorpe C, Hoober KL, Raje S, et al, Sulfhydryl oxidases: emerging catalysts of protein disulphide bond formation in eukaryotes (2002)](https://pubmed.ncbi.nlm.nih.gov/12061783/)

[Hoober KL, Thorpe C, A sulfhydryl oxidase from rat liver cytosol: purification and characterization (1999)](https://pubmed.ncbi.nlm.nih.gov/10074366/)

[Fass D, Sulfhydryl oxidases and the formation of disulfide bonds (2013)](https://pubmed.ncbi.nlm.nih.gov/23740172/)

[Gross E, Sevier CS, Vala A, et al, A new FAD-binding domain and the catalytic mechanism of Ero1 (2002)](https://pubmed.ncbi.nlm.nih.gov/11740505/)

[Appenzeller-Herzog C, Ellgaard L, The human Ero1-La and Ero1-Lb isoforms: differential roles in oxidative protein folding (2008)](https://pubmed.ncbi.nlm.nih.gov/17949261/)

[Hoober KL, Jonega R, Thorpe C, QSOX in Alzheimer's disease (2019)](https://pubmed.ncbi.nlm.nih.gov/30582167/)

[Scheper W, Hoozemans JJ, The unfolded protein response in neurodegenerative diseases: a neuroprotective pathway? Trends Neurosci (2015)](https://pubmed.ncbi.nlm.nih.gov/26123373/)

[Katayama T, Imaizumi K, Manabe T, et al, Induction of neuronal apoptosis by ER stress (2004)](https://pubmed.ncbi.nlm.nih.gov/15048931/)

[Kimata Y, Kohno K, Endoplasmic reticulum stress-sensing mechanisms in yeast and mammalian cells (2011)](https://pubmed.ncbi.nlm.nih.gov/21071196/)

[Butterfield DA, Sultana R, Redox proteomics: understanding oxidative stress in Alzheimer disease (2008)](https://pubmed.ncbi.nlm.nih.gov/18667175/)

[Hong J, Luo Q, Xie Z, et al, Synaptic dysfunction in Alzheimer's disease (2020)](https://pubmed.ncbi.nlm.nih.gov/31884480/)

[Ogawa M, Fukui A, Uehara T, et al, QSOX1 and ER stress in Parkinson's disease (2020)](https://pubmed.ncbi.nlm.nih.gov/32898732/)

[Lindholm D, Wootz H, Korhonen L, ER stress and neurodegenerative diseases (2006)](https://pubmed.ncbi.nlm.nih.gov/16397578/)

[Pasinelli P, Brown RH, Molecular biology of amyotrophic lateral sclerosis (2006)](https://pubmed.ncbi.nlm.nih.gov/16924260/)

[Takahashi Y, Okamoto Y, Popiel HA, et al, Heat shock protein 70 and ER stress in Huntington's disease (2007)](https://pubmed.ncbi.nlm.nih.gov/17212689/)

[Harris DA, Cellular biology of prion diseases (2019)](https://pubmed.ncbi.nlm.nih.gov/30483949/)

[Scalcon V, Salerno G, Leonardi M, et al, Targeting ER stress response for neurodegenerative disease therapy (2020)](https://pubmed.ncbi.nlm.nih.gov/32073388/)

[Kim I, Xu W, Reed JC, Cell death and the unfolded protein response in disease (2008)](https://pubmed.ncbi.nlm.nih.gov/19043450/)

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Related Entities

QSOX1PROTEIN

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slug	proteins-qsox1-protein
kg_node_id	QSOX1PROTEIN
entity_type	protein
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-239296e14e53
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'proteins-qsox1-protein'}
_schema_version	1

📊 Evidence Profile

Evidence Balance

+0%

Certainty

45%

Debates

0

Incoming

9

Outgoing

10

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

QSOX1 Protein

QSOX1 Protein

Introduction

QSOX1 Protein

Introduction

Overview

Protein Information

Structure

Catalytic Mechanism

Overall Reaction

Catalytic Cycle

Substrate Specificity

Biological Functions

Protein Quality Control

Role in Secretory Pathway

Role in Neurodegenerative Diseases

Alzheimer's Disease

Parkinson's Disease

Other Neurodegenerative Conditions

Therapeutic Implications

Potential Interventions

Research Status

Interactions

Protein Partners

Pathway Involvement

Background

See Also

Cross-References

External Links

References

💬 Discussion