Practice question

Conversion of testosterone into more potent dihydrotestosterone responsible for external genital masculinization is catalyzed not by hormone but by membrane enzyme steroid 5α-reductase type 2 encoded by SRD5A2 gene. Enzyme localized in genital skin, prostate and hair follicles uses NADPH to reduce testosterone double bond forming DHT. DHT binds androgen receptor with higher affinity and slower dissociation ensuring robust activation of male morphogenetic genes. Confusing hormone with enzyme is common, but catalytic step essential. In provided options intended catalyst for external genitalia virilization corresponds to 5α-reductase activity.