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sulfhydryl oxidase 1; hQSOX; quiescin Q6 (QSOX1 QSCN6 UNQ2520/PRO6013)
Function:
1) catalyzes the oxidation of sulfhydryl groups in peptide & protein thiols to disulfides with reduction of O2 to H2O2
2) disulfide bond formation in a variety of secreted proteins
3) in fibroblasts, growth regulation & tumor-suppressor (putative)
Cofactor: binds 1 FAD per subunit
Structure:
- monomer
- belongs to the quiescin-sulfhydryl oxidase (QSOX) family
- contains 1 ERV/ALR sulfhydryl oxidase domain
- contains 1 thioredoxin domain
Compartment:
- isoform 1: membrane
- isoform 2:
a) secreted
b) found in extracellular medium of quiescent cells but not found in proliferating cells
Alternative splicing: named isoforms=2
Expression:
- expressed in heart, placenta, lung, liver, skeletal muscle, pancreas > brain, kidney
- induced in quiescent cells (just as fibroblasts begin to leave proliferative cycle & enter quiescence)
Notes: 'Quiescin Q6' means that it was the 6th clone found at a higher level of expression in quiescent fibroblasts
General
flavoprotein
glycoprotein
membrane protein
oxidoreductase
Properties
SIZE: entity length = 747 aa
MW = 83 kD
COMPARTMENT: golgi
MOTIF: signal sequence {1-29}
thioredoxin domain
SITE: 36-156
MOTIF: cysteine residue {C70}
MODIFICATION: cysteine residue {C73}
cysteine residue {C70}
cysteine residue {C73}
cysteine residue {C73}
MODIFICATION: cysteine residue {C70}
N-glycosylation site {N130}
N-glycosylation site {N243}
cysteine residue {C393}
MODIFICATION: cysteine residue {C405}
ERV/ALR sulfhydryl oxidase {396-503}
MOTIF: binding site
SITE: 401-401
FOR-BINDING-OF: FAD
cysteine residue {C405}
MODIFICATION: cysteine residue {C393}
binding site
SITE: 408-408
FOR-BINDING-OF: FAD
binding site
SITE: 412-412
FOR-BINDING-OF: FAD
cysteine residue {C449}
MODIFICATION: cysteine residue {C452}
binding site
SITE: 451-451
FOR-BINDING-OF: FAD
cysteine residue {C452}
MODIFICATION: cysteine residue {C449}
binding site
SITE: 455-455
FOR-BINDING-OF: FAD
cofactor-binding site [478-485]
COFACTOR-BOUND: flavin adenine dinucleotide
binding site
SITE: 500-500
FOR-BINDING-OF: FAD
binding site
SITE: 503-503
FOR-BINDING-OF: FAD
cysteine residue {C509}
MODIFICATION: cysteine residue {C512}
cysteine residue {C512}
MODIFICATION: cysteine residue {C509}
N-glycosylation site {N575}
transmembrane domain {710-730}
Database Correlations
OMIM 603120
UniProt O00391
PFAM correlations
Entrez Gene 5768
Kegg hsa:5768
ENZYME 1.8.3.2
References
UniProt :accession O00391