Steroid 11-beta-hydroxylase

Cytochrome P450, family 11, subfamily B, polypeptide 1
Identifiers
Symbols	CYP11B1 ; CPN1; CYP11B; FHI; P450C11
External IDs	OMIM: 610613 MGI: 88584 HomoloGene: 128035 ChEMBL: 1908 GeneCards: CYP11B1 Gene
EC number	1.14.15.4
Gene ontology Molecular function • steroid 11-beta-monooxygenase activity • iron ion binding • heme binding Cellular component • mitochondrion • mitochondrial inner membrane Biological process • C21-steroid hormone biosynthetic process • glucocorticoid biosynthetic process • xenobiotic metabolic process • immune response • steroid metabolic process • regulation of blood pressure • sterol metabolic process • aldosterone biosynthetic process • cellular response to hormone stimulus • cortisol biosynthetic process • cellular response to potassium ion • glucose homeostasis • small molecule metabolic process • oxidation-reduction process Sources: Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	1584	13072
Ensembl	ENSG00000160882	ENSMUSG00000022589
UniProt	P15538	P15539
RefSeq (mRNA)	NM_000497	NM_009991
RefSeq (protein)	NP_000488	NP_034121
Location (UCSC)	Chr 8: 142.87 – 142.88 Mb	Chr 15: 74.85 – 74.86 Mb
PubMed search	[1]	[2]

Not to be confused with 11-Beta hydroxysteroid dehydrogenase.

Steroid 11β-hydroxylase is a steroid hydroxylase found in the zona glomerulosa and zona fasciculata. Named officially the cytochrome P450 11B1, mitochondrial, it is a protein that in humans is encoded by the CYP11B1 gene.

This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases that catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. This protein localizes to the mitochondrial inner membrane and is involved in the conversion of 11-deoxycortisol to cortisol in the adrenal cortex. Transcript variants encoding different isoforms have been noted for this gene.

It is reversibly inhibited by etomidate and metyrapone.

Function

steroid 11β-monooxygenase
Identifiers
EC number	1.14.15.4
CAS number	Template:CAS
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
Search PMC articles PubMed articles NCBI proteins

It generates cortisol from 11-deoxycortisol and corticosterone from 11-deoxycorticosterone. Note the extra "–OH" added at the 11 position (near the center, on ring "C"):

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  11-Deoxycortisol

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  Cortisol

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  11-deoxycorticosterone

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  Corticosterone

Mechanism of action

As a mitochondrial P450 system, P450c11 is dependent on two electron transfer proteins, adrenodoxin reductase and adrenodoxin that transfer 2 electrons from NADPH to the P450 for each monooxygenase reaction catalyzed by the enzyme. In most respects this process of electron transfer appears similar to that of P450scc system that catalyzes cholesterol side chain cleavage. Similar to P450scc the process of electrons transfer is leaky leading to superoxide production. The rate of electron leakage during metabolism depends on the functional groups of the steroid substrate.

Regulation

The expression of the enzyme in adrenocortical cells is regulated by the trophic hormone corticotropin (ACTH.

Clinical significance

A mutation is associated with congenital adrenal hyperplasia due to 11β-hydroxylase deficiency.

Additional images

Steroidogenesis, showing steroid 11-beta-hydroxylase vertically at right.

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  Corticosteroid biosynthetic pathway in rat

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  Steroid numbering

External links

• Steroid 11-beta-hydroxylase at the US National Library of Medicine Medical Subject Headings (MeSH)