5β-reductase

5β-Reductase

5β-Reductase is an enzyme that plays a crucial role in the metabolism of steroid hormones. It is responsible for the reduction of double bonds in steroid structures, specifically converting Δ4-3-ketosteroids into their 5β-dihydro forms. This enzyme is part of the aldo-keto reductase (AKR) family and is encoded by the AKR1D1 gene in humans.

Function

5β-Reductase catalyzes the reduction of the double bond between carbon atoms 4 and 5 in steroid hormones, such as progesterone and testosterone, resulting in the formation of 5β-dihydroprogesterone and 5β-dihydrotestosterone, respectively. This reaction is crucial for the inactivation of steroid hormones and their conversion into bile acids, which are essential for the digestion and absorption of dietary fats.

Clinical Significance

Mutations or deficiencies in the AKR1D1 gene can lead to disorders in bile acid synthesis, resulting in conditions such as congenital bile acid synthesis defect type 2. This can cause cholestasis, a condition characterized by impaired bile flow, leading to liver damage and other systemic effects.

5β-Reductase activity is also significant in the context of steroid metabolism and endocrinology, as it influences the levels and activity of various steroid hormones in the body.

Research and Applications

Research into 5β-reductase has implications for understanding and treating metabolic disorders, liver diseases, and certain types of cancer. Inhibitors of 5β-reductase are being studied for their potential therapeutic effects in these areas.

Also see

• Steroid metabolism
• Aldo-keto reductase
• Bile acid synthesis
• Cholestasis
• Endocrinology