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{{enzyme 
| EC_number = 1.1.1.149
| IUBMB_EC_number =  1/1/1/149
| CAS_number= 9040-08-8
| Name =  20-α-hydroxysteroid dehydrogenase
| GO_code = 0047006
| image = 
| width = 
| caption = 
}}

In [[enzymology]], a '''20-α-hydroxysteroid dehydrogenase''' ({{EC number|1.1.1.149}}) is an [[enzyme]] that [[catalysis|catalyzes]] the [[chemical reaction]]

:17alpha,20alpha-dihydroxypregn-4-en-3-one + NAD(P)<sup>+</sup> <math>\rightleftharpoons</math> 17alpha-hydroxyprogesterone + NAD(P)H + H<sup>+</sup>

The 3 [[substrate (biochemistry)|substrates]] of this enzyme are [[17alpha,20alpha-dihydroxypregn-4-en-3-one]], [[nicotinamide adenine dinucleotide|NAD<sup>+</sup>]], and [[nicotinamide adenine dinucleotide phosphate|NADP<sup>+</sup>]], whereas its 4 [[product (chemistry)|products]] are [[17-alpha-hydroxyprogesterone]], [[nicotinamide adenine dinucleotide|NADH]], [[nicotinamide adenine dinucleotide phosphate|NADPH]], and [[hydrogen ion|H<sup>+</sup>]].

This enzyme belongs to the family of [[oxidoreductase]]s, specifically those acting on the CH-OH group of donor with NAD<sup>+</sup> or NADP<sup>+</sup> as acceptor. The systematic name of this enzyme class is '''20alpha-hydroxysteroid:NAD(P)<sup>+</sup> 20-oxidoreductase'''. Other names in common use include '''20alpha-hydroxy steroid dehydrogenase''', '''20alpha-hydroxy steroid dehydrogenase''', '''20alpha-HSD''', and '''20alpha-HSDH'''. This enzyme participates in [[c21-steroid hormone metabolism]].

20alpha-HSD has been initially described as a progesterone metabolizing enzyme of the ovary. On a functional level, ovarian 20alpha-HSD is actively involved in the control of progesterone homeostasis in pregnancy of rats and mice. While 20alpha-HSD expression and activity is downregulated in the corpus luteum of pregnancy, 24 hrs prior to parturition ovarian 20alpha-HSD activity is acutely stimulated. Accordingly, in mice with targeted deletion of the 20alpha-HSD gene, progesterone blood concentration remain high throughout pregnancy which results in a delay of 2–4 days in parturition. Indicating that expression of 20alpha-HSD activity is mandatory for the induction of parturition through reduction of progesterone blood concentration. In mice, 20alpha-HSD is also expressed in the adrenals, kidneys, brain, thymus, T cells and bone marrow. Its induction in hematopoietic cells was used as an assay for the identification of T cell derived factor interleukin-3. In addition, the enzyme reduces and inactivates 17-deoxycorticosterone, the precursor of aldosterone and corticosterone.

==Structural studies==

As of late 2007, 3 [[tertiary structure|structures]] have been solved for this class of enzymes, with [[Protein Data Bank|PDB]] accession codes {{PDB link|1MRQ}}, {{PDB link|1Q13}}, and {{PDB link|1Q5M}}.

== See also ==

* [[3beta(or 20alpha)-hydroxysteroid dehydrogenase|3β(or 20α)-hydroxysteroid dehydrogenase]]

==References==
{{reflist}}

==Further reading==
{{refbegin | 2}}

* {{cite journal | author = Shikita M, Inano H, Tamaoki B | year = 1967 | title = Further studies on 20-alpha-hydroxysteroid dehydrogenase of rat testes | journal = Biochemistry. | volume = 6 | pages = 1760&ndash;4 | pmid = 4382486 | doi = 10.1021/bi00858a026 | issue = 6 }}
* {{cite journal | author = Strickler RC, Tobias B, Covey DF | year = 1981 | title = Human placental 17 beta-estradiol dehydrogenase and 20 alpha-hydroxysteroid dehydrogenase. Two activities at a single enzyme active site | journal = J. Biol. Chem. | volume = 256 | pages = 316&ndash;21 | pmid = 6935192 | issue = 1 }}
* {{cite journal | author = Wiest WG, Kidwell WR, Balogh K | title = Progesterone catabolism in the rat ovary: a regulatory mechanism for progestational potency during pregnancy | journal = Endocrinology | volume = 82 | issue = 4 | pages = 844–59 |date=April 1968 | pmid = 5742200 | doi = 10.1210/endo-82-4-844| url = | issn = }}

* {{cite journal | author = Wiest WG | title = On the function of 20 alpha-hydroxypregn-4-en-3-one during parturition in the rat | journal = Endocrinology | volume = 83 | issue = 6 | pages = 1181–4 |date=December 1968 | pmid = 5721991 | doi = 10.1210/endo-83-6-1181| url = | issn = }}

* {{cite journal | author = Piekorz RP, Gingras S, Hoffmeyer A, Ihle JN, Weinstein Y | title = Regulation of progesterone levels during pregnancy and parturition by signal transducer and activator of transcription 5 and 20alpha-hydroxysteroid dehydrogenase | journal = Mol. Endocrinol. | volume = 19 | issue = 2 | pages = 431–40 |date=February 2005 | pmid = 15471942 | doi = 10.1210/me.2004-0302 | url = | issn = }}

* {{cite journal | author = Akinola LA, Poutanen M, Vihko R, Vihko P | title = Expression of 17beta-hydroxysteroid dehydrogenase type 1 and type 2, P450 aromatase, and 20alpha-hydroxysteroid dehydrogenase enzymes in immature, mature, and pregnant rats | journal = Endocrinology | volume = 138 | issue = 7 | pages = 2886–92 |date=July 1997 | pmid = 9202232 | doi = 10.1210/en.138.7.2886| url = | issn = }}

* {{cite journal | author = Weinstein Y | title = 20alpha-hydroxysteroid dehydrogenase: a T lymphocyte-associated enzyme | journal = J. Immunol. | volume = 119 | issue = 4 | pages = 1223–9 |date=October 1977 | pmid = 302277 | doi = | url = | issn = }}

* {{cite journal | author = Weinstein Y, Lindner HR, Eckstein B | title = Thymus metabolises progesterone- possible enzymatic marker for T lymphocytes | journal = Nature | volume = 266 | issue = 5603 | pages = 632–3 |date=April 1977 | pmid = 300849 | doi = 10.1038/266632a0| url = | issn = }}

* {{cite journal | author = Ihle JN, Keller J, Oroszlan S, Henderson LE, Copeland TD, Fitch F, Prystowsky MB, Goldwasser E, Schrader JW, Palaszynski E, Dy M, Lebel B | title = Biologic properties of homogeneous interleukin 3. I. Demonstration of WEHI-3 growth factor activity, mast cell growth factor activity, p cell-stimulating factor activity, colony-stimulating factor activity, and histamine-producing cell-stimulating factor activity | journal = J. Immunol. | volume = 131 | issue = 1 | pages = 282–7 |date=July 1983 | pmid = 6190911 | doi = | url = | issn = }}

* {{cite journal | author = Hershkovitz L, Beuschlein F, Klammer S, Krup M, Weinstein Y | title = Adrenal 20alpha-hydroxysteroid dehydrogenase in the mouse catabolizes progesterone and 11-deoxycorticosterone and is restricted to the X-zone | journal = Endocrinology | volume = 148 | issue = 3 | pages = 976–88 |date=March 2007 | pmid = 17122075 | doi = 10.1210/en.2006-1100 | url = | issn = }}
{{refend}}

[[Category:EC 1.1.1]]
[[Category:NADPH-dependent enzymes]]
[[Category:NADH-dependent enzymes]]
[[Category:Enzymes of known structure]]


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