Quiescin Q6 Sulfhydryl Oxidase 1 (QSOX1)

Sulfhydryl oxidase 1 is a protein that contains domains of thioredoxin and ERV1, members of two long-standing gene families. The gene expression is induced as fibroblasts begin to exit the proliferative cycle and enter quiescence, suggesting that this gene plays an important role in growth regulation. Two transcript variants encoding two different isoforms have been found for this gene.

Coppock et al. (1993) isolated human embryo lung fibroblast cDNAs that were expressed at a higher level in quiescent cells than in logarithmically growing cells. Several partial cDNAs corresponded to the QSOX1 gene, which the authors called Q6. Northern blot analysis revealed that Q6 is expressed as 3- and 4-kb mRNAs in embryo lung fibroblasts.