sulfhydryl oxidase 1; hQSOX; quiescin Q6 (QSOX1 QSCN6 UNQ2520/PRO6013)

Function

• catalyzes the oxidation of sulfhydryl groups in peptide & protein thiols to disulfides with reduction of O2 to H2O2
• disulfide bond formation in a variety of secreted proteins
• 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:
  • secreted
  • 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

More general terms

• flavoprotein
• oxidoreductase
• glycoprotein
• membrane protein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=5768
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:5768
• OMIM: https://mirror.omim.org/entry/603120
• UniProt: http://www.uniprot.org/uniprot/O00391.html