Human Srx is located on chromosome 20 in the region of p13.

Human Srx gene is 6632 bp in length, composed of 2 exons and located at chromosome 20p13.

The size of Srx mRNA is 2580 bp. Srx transcript contains two exons. Exon 1 is 271 bp and exon 2 is 2300 bp. The catalytic domain of Srx reducing enzyme activity is localized in exon 2.

Human Srx protein has a total of 137 amino acids and a 14 kDa molecular weight.

Srx is a member of antioxidant protein family containing a ParB-like nuclease domain. It forms 5 beta strands and 6 helix secondary structures. Srxn1 binds to peroxiredoxins (Prxs) and reduces overoxidized Prxs in the presence of cofactors including magnesium and ATP.

In adult, Srx protein was found in internal organs such as mouse liver and kidney. Expression pattern of Srx in embryonic development is not clear. Transcriptional regulation of Srx expression is mainly mediated through AP-1 and/or Nrf-2 activation (Jeong et al., 2012). In yeast, it may also be negatively regulated at the translational level through Ras-PKA pathway (Molin et al., 2011).

Srx is mainly localized in the cytosol. In the presence of severe oxidative stress, it may also translocate to mitochondria (Noh et al., 2009).

Srx was first identified as a gene preferentially expressed in transformed JB6 cells (Sun et al., 1994). The primary biochemical function of Srx is to reduce the overoxidized cysteine residues of Prx I, Prx II, Prx III and Prx IV under severe oxidative stress (Biteau et al., 2003; Chang et al., 2004). The spectrum and specificity of its enzymatic function remains elusive. Srx may also cause the deglutathionylation of Prx II and others (Park et al., 2009; Findlay et al., 2006). The biological function of Srx may involve in the regulation of various cell signaling pathways to promote tumorigenesis and cancer progression. Abnormally high expression of Srx has been demonstrated in many malignant tumors including those of skin, lung, and colon (Wei et al., 2008). Srx may not be essential for development since Srx null mice are viable and normal (Planson et al., 2011).

Srx gene is conserved among species, from metazoan to human.