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21-Hydroxylase

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Title: 21-Hydroxylase  
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Subject: Cyproterone acetate, Cyanoketone, Metyrapone, 20α,22R-Dihydroxycholesterol, 22R-Hydroxycholesterol
Collection: Cytochrome P450, Ec 1.14.99, Human Proteins, Metabolism
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21-Hydroxylase

Steroid 21-monooxygenase
Identifiers
EC number 1.14.99.10
CAS number 9029-68-9
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / EGO
Cytochrome P450, family 21, subfamily A, polypeptide 2
Available structures
PDB Ortholog search: PDBe, RCSB
Identifiers
Symbols  ; CA21H; CAH1; CPS1; CYP21; CYP21B; P450c21B
External IDs ChEMBL: GeneCards:
EC number
RNA expression pattern
Orthologs
Species Human Mouse
Entrez
Ensembl
UniProt
RefSeq (mRNA)
RefSeq (protein)
Location (UCSC)
PubMed search

Steroid 21-hydroxylase is a cytochrome P450 enzyme that is involved with the biosynthesis of the steroid hormones aldosterone and cortisol.[1]

In humans, 21-Hydroxylase is encoded by the gene CYP21A2.[2]

Contents

  • Names and classification 1
  • Function 2
  • Reaction 3
  • Pathway 4
  • Clinical significance 5
  • References 6
  • Further reading 7
  • External links 8

Names and classification

21-Hydroxylase is also called steroid 21-monooxygenase, 21α-Hydroxylase, and, less commonly 21β-Hydroxylase.

Function

This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. This protein localizes to the endoplasmic reticulum and hydroxylates steroids at the 21 position. Its activity is required for the synthesis of steroid hormones including cortisol and aldosterone.[3]

Reaction

21-Hydroxylase catalyses the hydroxylation of the carbon atom 21 in steroids (adding an "–OH"), which is necessary with the formation of these hormones.

Steroid numbering - #21 is near center top 

Pathway

Human steroidogenesis, showing both reactions of 21-Hydroxylase at center top.
Corticosteroid biosynthetic pathway in the rat.

Clinical significance

A defect within the CYP21A2 gene causes a disturbance of the development of the enzyme, which leads to congenital adrenal hyperplasia due to 21-hydroxylase deficiency. A related pseudogene is located near this gene; gene conversion events involving the functional gene and the pseudogene are thought account for many cases of steroid 21-hydroxylase deficiency.[3]

References

  1. ^ Ryan KJ, Engel LL (March 1957). "Hydroxylation of steroids at carbon 21". J. Biol. Chem. 225 (1): 103–14.  
  2. ^ Higashi Y, Yoshioka H, Yamane M, Gotoh O, Fujii-Kuriyama Y (May 1986). "Complete nucleotide sequence of two steroid 21-hydroxylase genes tandemly arranged in human chromosome: a pseudogene and a genuine gene". Proc. Natl. Acad. Sci. U.S.A. 83 (9): 2841–5.  
  3. ^ a b "Entrez Gene: CYP21A2 cytochrome P450, family 21, subfamily A, polypeptide 2". 

Further reading

  • White PC, Tusie-Luna MT, New MI, Speiser PW (1994). "Mutations in steroid 21-hydroxylase (CYP21).". Hum. Mutat. 3 (4): 373–8.  
  • Helmberg A (1993). "Twin genes and endocrine disease: CYP21 and CYP11B genes.". Acta Endocrinol. 129 (2): 97–108.  
  • de-Araujo M, Sanches MR, Suzuki LA, et al. (1996). "Molecular analysis of CYP21 and C4 genes in Brazilian families with the classical form of steroid 21-hydroxylase deficiency.". Braz. J. Med. Biol. Res. 29 (1): 1–13.  
  • Yu CY (1999). "Molecular genetics of the human MHC complement gene cluster.". Exp. Clin. Immunogenet. 15 (4): 213–30.  
  • Forest MG, Tardy V, Nicolino M, et al. (2005). "21-Hydroxylase deficiency: an exemplary model of the contribution of molecular biology in the understanding and management of the disease.". Ann. Endocrinol. (Paris) 66 (3): 225–32.  

External links

  • GeneReviews/NCBI/NIH/UW entry on 21-Hydroxylase-Deficient Congenital Adrenal Hyperplasia
  • OMIM entry on 21-Hydroxylase-Deficient Congenital Adrenal Hyperplasia
  • Synthesis of Desoxycorticosterone from Progesterone through 21-Hydroxylase (Image)
  • Steroid 21-Hydroxylase at the US National Library of Medicine Medical Subject Headings (MeSH)

This article incorporates text from the United States National Library of Medicine, which is in the public domain.

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