The function of ENSG00000176946 (THAP4, THAP domain containing 4) is as follows. Heme-binding protein able to scavenge peroxynitrite and to protect free L-tyrosine against peroxynitrite-mediated nitration, by acting as a peroxynitrite isomerase that converts peroxynitrite to nitrate. Therefore, this protein likely plays a role in peroxynitrite sensing and in the detoxification of reactive nitrogen and oxygen species (RNS and ROS, respectively). Is able to bind nitric oxide (NO) in vitro, but may act as a sensor of peroxynitrite levels in vivo, possibly modulating the transcriptional activity residing in the N- terminal region. {ECO:0000269|PubMed:30524950, ECO:0000269|PubMed:32295384}.