Binds tetrapyrroles and promotes the photooxidative degradation of protoporphyrin IX (PubMed:23651039). Can bind the benzodiazepine receptor agonist PK-11195 (in vitro); this interferes with photooxidative tetrapyrrole degradation (PubMed:23651039). May play a role in the transmembrane transport of tetrapyrroles and similar compounds (By similarity). Belongs to the TspO/BZRP family.