5 alpha Reductase

Steroid 5-α reductase (5AR) is a membrane-bound protein that is responsible for reducing steroids such as testosterone, progesterone, and androstenedione to 5-α reduced metabolites such as 5-α dihydrotestosterone (DHT), 5-α dihydroprogesterone and androstanedione, respectively. There are three isoforms of 5AR in humans: SRD5A1, SRD5A2, and SRD5A3. SRD5A1 and SRD5A2 have functionality for 5-α reduction of steroids in humans. DHT is a more potent androgen than testosterone and has a function in androgen receptor activation.

The inactivating mutations in 5αR2 lead to disorders of sexual development. The regulation of 5AR is important for the treatment of benign prostate hyperplasia (BPH) and prostate cancer (PC), and 5AR inhibitors are widely used for the treatment of androgen-dependent benign or malignant prostatic diseases.