Selenoprotein N (SELENON)

Isoform 2: Plays an essential role in cell protection against oxidative stress and in the regulation of redox-related calcium homeostasis. Regulates the calcium level of the ER by protecting the calcium pump ATP2A2 against the oxidoreductase ERO1A-mediated oxidative damage.

Within the ER, ERO1A activity raises the concentration of H(2)O(2), which attacks the luminal thiols in ATP2A2 and thus results in cysteinyl sulfenic acid formation (-SOH) and SEPN1 reduces the SOH back to free thiol (- SH), thus restoring ATP2A2 action (PubMed:25452428). Acts as a modulator of ryanodine receptor (RyR) action: protects RyR from oxidation due to increased oxidative stress, or directly controls the RyR redox state, regulating the RyR-mediated calcium mobilization needed for normal muscle development and differentiation (PubMed:19557870, PubMed:18713863).