A NAD(P)H-dependent oxidoreductase involved in cellular oxidative stress response. At the plasma membrane, catalyzes reduction of coenzyme Q/ubiquinone-10 to ubiquinol-10, a lipophilic radical-trapping antioxidant that prevents lipid oxidative damage and consequently ferroptosis. Cooperates with GPX4 to suppress phospholipid peroxidation and ferroptosis. This anti-ferroptotic function is independent of cellular glutathione levels (PubMed:31634899, PubMed:31634900). May play a role in mitochondrial stress signaling. Upon oxidative stress, associates with the lipid peroxidation end product 4-hydroxy-2-nonenal (HNE) forming a lipid adduct devoid of oxidoreductase activity, which then translocates from mitochondria into the nucleus triggering DNA damage and cell death (PubMed:26689472). Capable of DNA binding in a non-sequence specific way (PubMed:15958387). H(+) + NADH + ubiquinone-10 = NAD(+) + ubiquinol-10 Binds 6-hydroxy-FAD non-covalently. The modification by 4-hydroxy-2-nonenal (HNE) adduction in mitochondria results in loss of the oxidoreductase activity and activation of a novel function in mitochondrial oxidative stress signaling. Interacts with importin subunits KPNA2 and IPO5; this interaction likely mediates the translocation into the nucleus upon oxidative stress. Detected in most normal tissues as two transcripts of 1.8 and 4.0 kb in length, respectively. Highly expressed in heart, moderately in liver and skeletal muscles, and expressed at low levels in placenta, lung, kidney, and pancreas. Both transcripts expressed following p53/TP53 induction. The shorter 1.8 kb transcript seems to be the major transcript in EB1 colon cancer cells. Expression detected at 4 hours after induction by p53/TP53. Down-regulated in a wide range of human tumors. N-myristoylation at Gly-2 mediates the recruitment to lipid droplets and plasma membrane. Belongs to the FAD-dependent oxidoreductase family. Conflicting data exist on the pro-apoptotic function of the protein. It was initially claimed that overexpression of FSP1 induces caspase-independent apoptosis, but new evidence disputes this function.