Function
Involved in oxidative stress response and redox homeostasis. Functions as a sensor and transducer of hydroperoxide stress. In response to hydroperoxide stress it oxidizes (activates) the transcription activator CAP1, which is involved in transcription activation of genes of the oxidative stress response pathway (PubMed:23706023). May also play a direct role in hydroperoxide scavenging. The enzyme is not required for the glutaredoxin-mediated antioxidant function. In the presence of peroxides, GPX3 is directly oxidized at Cys-43 to form a cysteine sulfenic acid (-SOH). Cys-43-SOH then forms either an intramolecular disulfide bond (Cys-43 with Cys-89) or a transient, intermolecular disulfide bond with 'Cys-446' of CAP1, which is further resolved into a CAP1 intramolecular disulfide bond ('Cys-303' with 'Cys-598'), which causes its nuclear accumulation and activation, and a reduced Cys-43 in GPX3 (By similarity). Required for C.albicans-mediated macrophage killing (PubMed:23706023).