5α-Pregnane-3α,17α-diol-20-one, also known as 17α-hydroxyallopregnanolone (17-OH-allo) is an

endogenous Endogenous substances and processes are those that originate from within a living system such as an organism, tissue, or cell. In contrast, exogenous substances and processes are those that originate from outside of an organism. For example, es ...

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...

Function

5α-Pregnane-3α,17α-diol-20-one is an intermediate product within the

androgen backdoor pathway The androgen backdoor pathway is a collective name for all metabolic pathways where clinically relevant androgens are synthesized with roundabout of testosterone as an intermediate product. Initially described as pathway where 5α-reduction of 17α ...

in which

17α-hydroxyprogesterone 17α-Hydroxyprogesterone (17α-OHP), also known as 17-OH progesterone (17-OHP), or hydroxyprogesterone (OHP), is an endogenous progestogen steroid hormone related to progesterone. It is also a chemical intermediate in the biosynthesis of many ot ...

(17‐OHP) is 5α-reduced and finally converted to

5α-dihydrotestosterone Dihydrotestosterone (DHT, 5α-dihydrotestosterone, 5α-DHT, androstanolone or stanolone) is an endogenous androgen sex steroid and hormone. The enzyme 5α-reductase catalyzes the formation of DHT from testosterone in certain tissues including ...

(DHT) without

testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testes and prostate, as well as promoting secondar ...

as a

metabolic intermediate Metabolic intermediates are molecules that are the precursors or metabolites of biologically significant molecules. Although these intermediates are of relatively minor direct importance to cellular function, they can play important roles in the a ...

. The pathway can be outlined as 17-OHP →

5α-pregnan-17α-ol-3,20-dione 5α-Pregnan-17α-ol-3,20-dione, also known as 17α-hydroxy-dihydroprogesterone (17‐OH-DHP) is an endogenous steroid. Function 5α-Pregnan-17α-ol-3,20-dione is the first intermediate product within the androgen backdoor pathway in which 17α-hydr ...

→ 5α-pregnane-3α,17α-diol-20-one → androsterone → 5α-androstane-3α,17β-diol → DHT.

Biosynthesis

5α-Pregnane-3α,17α-diol-20-one is produced from

in a reaction catalyzed by a reductive 3α-hydroxysteroid dehydrogenase (3α-HSD), i.e. by the two aldo-keto reductase isozymes:

AKR1C2 Aldo-keto reductase family 1 member C2, also known as bile acid binding protein, 3α-hydroxysteroid dehydrogenase type 3, and dihydrodiol dehydrogenase type 2, is an enzyme that in humans is encoded by the ''AKR1C2'' gene. This gene encodes a m ...

and AKR1C4, and by 17β-hydroxysteroid dehydrogenase 6 (

HSD17B6 Hydroxysteroid 17-beta dehydrogenase 6 is an enzyme that in humans is encoded by the ''HSD17B6'' gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''g ...

) that also has the 3α-HSD activity.

References

{{Endogenous steroids Pregnanes 5α-Pregnanes

Function

Biosynthesis

See also

References