Steroid 5-alpha-reductase type 1 and type 2 (5α-Reductase type 1 (SRD5A1), 5α-Reductase type 2 (SRD5A2))

Steroid 5-alpha-reductase type 1 and type 2 are membrane-bound, NADPH-dependent enzymes that catalyze the irreversible conversion of testosterone to dihydrotestosterone (DHT), a highly potent androgen[1][2][3]. Type 1 and type 2 isoforms are encoded by the SRD5A1 and SRD5A2 genes, respectively, and are major components of androgen signaling in tissues such as prostate, skin, liver, and reproductive organs[2][3][5]. These enzymes are critical for the development of male external genitalia and secondary sexual characteristics, and their dysregulation or deficiency leads to a spectrum of androgen-related disorders including benign prostatic hyperplasia, prostate cancer, and male pseudohermaphroditism[3][5][6]. Inhibitors of these enzymes (notably finasteride and dutasteride) are widely used in the treatment of BPH and androgen-dependent pathologies due to their ability to lower DHT levels and thus attenuate androgen receptor signaling[2][6].

Other names

5α-reductase type I5α-reductase type IISRD5A1SRD5A2testosterone 5α-reductase

Competitive inhibition of enzyme activity (block the conversion of testosterone to DHT); Androgen modulation/reduction in DHT-mediated signaling