17β-Hydroxysteroid dehydrogenase 1 (17β-HSD1) is an enzyme that in humans is encoded by the HSD17B1gene.[5][6][7] This enzyme oxidizes or reduces the C17 hydroxy/keto group of androgens and estrogens and hence is able to regulate the potency of these sex steroids
The human 17β-HSD1 isozyme is highly specific for estrogens over androgens whereas the rodent isozyme is less specific.[8]
Discovery
Human 17β-HSD1 was the first enzyme of the 17β-HSD family to be cloned and to have its sequence identified.[9][10] Its three-dimensional structure is also the first example of any human steroid-converting enzyme.[11]
Structure
This enzyme contains a short-chain dehydrogenase domain that contains a characteristic 3-layer (αβα) sandwich known as a Rossmann fold. The human enzyme contains 327 amino acids and exists as a homodimer with two identical subunits of 34.5 kDa [10][12] The N-terminal short-chain dehydrogenase domain contains binding site for the NADP+/NADPH cofactor. A narrow, hydrophobic C-terminal domain contains a binding pocket for the steroid substrate.
Clinical significance
Estradiol stimulates while dihydrotestosterone (DHT) inhibits breast cancer growth. Furthermore 17β-HSD1 levels positively correlate with estradiol and negatively correlate with DHT levels in breast cancer cells. Hence 17β-HSD1 represents a possible drug target for breast cancer treatment.[13]
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Normand T, Narod S, Labrie F, Simard J (Apr 1993). "Detection of polymorphisms in the estradiol 17 beta-hydroxysteroid dehydrogenase II gene at the EDH17B2 locus on 17q11-q21". Human Molecular Genetics. 2 (4): 479–83. doi:10.1093/hmg/2.4.479. PMID8389226.
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