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A reference for what the literature reports. Not medical advice.

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Proteins/UNIPROT:P08686

CYP21A2

Protein·UNIPROT:P08686Steroid 21-hydroxylase

Open in the graph

A cytochrome P450 monooxygenase that plays a major role in adrenal steroidogenesis. Catalyzes the hydroxylation at C-21 of progesterone and 17alpha-hydroxyprogesterone to respectively form 11-deoxycorticosterone and 11-deoxycortisol, intermediate metabolites in the biosynthetic pathway of mineralocorticoids and glucocorticoids. Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate, and reducing the second into a water molecule, with two electrons provided by NADPH via cytochrome P450 reductase (CPR; NADPH-ferrihemoprotein reductase)..

Function from UniProtKB (P08686), read 2026-09-23. CC BY 4.0.

Curated compounds routed: 0

What the reference databases state

Inferred

Inferred — not reported by a source. Evidence key

GenCC submitters' classifications

3 rows

classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency has a germline basis in CYP21A2DiseaseGenCC HGNC:2600|MONDO:0008728Inferred only
classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency, salt wasting form has a germline basis in CYP21A2DiseaseGenCC HGNC:2600|MONDO:0017839Inferred only
classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency, simple virilizing form has a germline basis in CYP21A2DiseaseGenCC HGNC:2600|MONDO:0017840Inferred only

Statements

40 statements

40 statements · 7 reference databases · Subject: CYP21A2 · Sources: Bgee, Human Protein Atlas, Human-GEM, Reactome, Rhea, UniProt, WikiPathways

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CYP21A2 is expressed in adrenal glandAnatomyHuman Protein Atlas ENSG00000231852Inferred only
CYP21A2 is expressed in adrenal glandAnatomyBgee ENSG00000231852Inferred only
CYP21A2 is expressed in left adrenal glandAnatomyBgee ENSG00000231852Inferred only
CYP21A2 is expressed in left adrenal gland cortexAnatomyBgee ENSG00000231852Inferred only
CYP21A2 is expressed in right adrenal glandAnatomyBgee ENSG00000231852Inferred only
CYP21A2 is expressed in right adrenal gland cortexAnatomyBgee ENSG00000231852Inferred only
11beta-hydroxyprogesterone is metabolised by CYP21A2CompoundHuman-GEM MAR01992Inferred only
17alpha-hydroxypregnenolone is metabolised by CYP21A2CompoundHuman-GEM MAR01948Inferred only
17alpha-hydroxyprogesterone is metabolised by CYP21A2CompoundHuman-GEM MAR01988Inferred only
17alpha-hydroxyprogesterone is metabolised by CYP21A2CompoundRhea RHEA:50308Inferred only
17alpha-hydroxyprogesterone is metabolised by CYP21A2CompoundHuman-GEM MAR07928Inferred only
3alpha-hydroxy-5alpha-pregnan-20-one is metabolised by CYP21A2CompoundHuman-GEM MAR03038Inferred only

Show the remaining 28

3alpha-hydroxy-5alpha-pregnan-20-one is metabolised by CYP21A2CompoundHuman-GEM MAR02005Inferred only
cortisol is metabolised by CYP21A2CompoundHuman-GEM MAR01990Inferred only
pregnenolone is metabolised by CYP21A2CompoundHuman-GEM MAR01940Inferred only
progesterone is metabolised by CYP21A2CompoundRhea RHEA:50304Inferred only
progesterone is metabolised by CYP21A2CompoundHuman-GEM MAR07932Inferred only
progesterone is metabolised by CYP21A2CompoundHuman-GEM MAR02007Inferred only
CYP21A2 participates in Biological oxidationsPathwayReactome R-HSA-211859Inferred only
CYP21A2 participates in Classical pathway of steroidogenesis with glucocorticoid and mineralocorticoid metabolismPathwayWikiPathways WP4523Inferred only
CYP21A2 participates in Corticotropin releasing hormone signalingPathwayWikiPathways WP2355Inferred only
CYP21A2 participates in Cytochrome P450 - arranged by substrate typePathwayReactome R-HSA-211897Inferred only
CYP21A2 participates in Defective CYP21A2 causes AH3PathwayReactome R-HSA-5579021Inferred only
CYP21A2 participates in DiseasePathwayReactome R-HSA-1643685Inferred only
CYP21A2 participates in Diseases of metabolismPathwayReactome R-HSA-5668914Inferred only
CYP21A2 participates in Endogenous sterolsPathwayReactome R-HSA-211976Inferred only
CYP21A2 participates in Glucocorticoid biosynthesisPathwayReactome R-HSA-194002Inferred only
CYP21A2 participates in Glucocorticoid biosynthesisPathwayWikiPathways WP5280Inferred only
CYP21A2 participates in Metabolic disorders of biological oxidation enzymesPathwayReactome R-HSA-5579029Inferred only
CYP21A2 participates in MetabolismPathwayReactome R-HSA-1430728Inferred only
CYP21A2 participates in Metabolism of lipidsPathwayReactome R-HSA-556833Inferred only
CYP21A2 participates in Metabolism of steroid hormonesPathwayReactome R-HSA-196071Inferred only
CYP21A2 participates in Metabolism of steroidsPathwayReactome R-HSA-8957322Inferred only
CYP21A2 participates in Metapathway biotransformation Phase I and IIPathwayWikiPathways WP702Inferred only
CYP21A2 participates in Mineralocorticoid biosynthesisPathwayReactome R-HSA-193993Inferred only
CYP21A2 participates in Mineralocorticoid biosynthesisPathwayWikiPathways WP5279Inferred only
CYP21A2 participates in Phase I - Functionalization of compoundsPathwayReactome R-HSA-211945Inferred only
CYP21A2 participates in Renin angiotensin aldosterone system RAAS PathwayWikiPathways WP4756Inferred only
CYP21A2 participates in Steroid hormone precursor biosynthesisPathwayWikiPathways WP5277Inferred only
CYP21A2 requires the cofactor heme bCompoundUniProt P08686Inferred only

Reactions

12 reactions

proton+NADPH(4-)+dioxygen+pregnenoloneMAM00605c+water+NADP(3-)
Catalysed by CYP21A2
Reaction pageLeft to rightBalancedEC 1.14.14.16cytosol
Human-GEM MAR01940CC BY 4.0Reference data
17alpha-hydroxypregnenolone+proton+NADPH(4-)+dioxygen17alpha,21-dihydroxypregnenolone

Other names

8 names

Resolves to: CYP21A2

Also called: 21-OHaseCYP21CYP21BCytochrome P-450c21Cytochrome P450 21Cytochrome P450 XXICytochrome P450-C21Cytochrome P450-C21B

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Catalysed by CYP21A2

Reaction pageLeft to rightBalancedEC 1.14.14.16cytosol

Human-GEM MAR01948CC BY 4.0Reference data

17alpha-hydroxyprogesterone+proton+NADPH(4-)+dioxygen11-deoxycortisol+water+NADP(3-)

Catalysed by CYP21A2

Reaction pageLeft to rightBalancedEC 1.14.14.16cytosol

Human-GEM MAR01988CC BY 4.0Reference data

cortisol+water+NADP(3-)MAM00603c+proton+NADPH(4-)+dioxygen

Catalysed by CYP21A2

Reaction pageLeft to rightBalancedEC 1.14.14.16cytosol

Human-GEM MAR01990CC BY 4.0Reference data

11beta-hydroxyprogesterone+proton+NADPH(4-)+dioxygencorticosterone+water+NADP(3-)

Catalysed by CYP21A2

Reaction pageLeft to rightBalancedEC 1.14.14.16cytosol

Human-GEM MAR01992CC BY 4.0Reference data

3alpha-hydroxy-5alpha-pregnan-20-one+proton+NADH(2-)+dioxygenMAM00604c+water+NAD(+)

Catalysed by CYP21A2

Reaction pageLeft to rightBalancedEC 1.14.14.16cytosol

Human-GEM MAR02005CC BY 4.0Reference data

proton+NADPH(4-)+dioxygen+progesterone21-hydroxyprogesterone+water+NADP(3-)

Catalysed by CYP21A2

Reaction pageLeft to rightBalancedEC 1.14.14.16cytosol

Human-GEM MAR02007CC BY 4.0Reference data

3alpha-hydroxy-5alpha-pregnan-20-one+proton+NADH(2-)+dioxygenMAM00604r+water+NAD(+)

Catalysed by CYP21A2

Reaction pageLeft to rightBalancedEC 1.14.14.16endoplasmic reticulum

Human-GEM MAR03038CC BY 4.0Reference data

17alpha-hydroxyprogesterone+proton+NADPH(4-)+dioxygen11-deoxycortisol+water+NADP(3-)

Catalysed by CYP21A2

Reaction pageLeft to rightBalancedEC 1.14.14.16endoplasmic reticulum

Human-GEM MAR07928CC BY 4.0Reference data

proton+NADPH(4-)+dioxygen+progesterone21-hydroxyprogesterone+water+NADP(3-)

Catalysed by CYP21A2

Reaction pageLeft to rightBalancedEC 1.14.14.16endoplasmic reticulum

Human-GEM MAR07932CC BY 4.0Reference data

progesterone+reduced [NADPH--hemoprotein reductase]+dioxygen21-hydroxyprogesterone+oxidized [NADPH--hemoprotein reductase]+water+hydron

Catalysed by CYP21A2

Reaction pageLeft to rightBalance undeterminable

Rhea RHEA:50304CC BY 4.0Reference data

17alpha-hydroxyprogesterone+reduced [NADPH--hemoprotein reductase]+dioxygen11-deoxycortisol+oxidized [NADPH--hemoprotein reductase]+water+hydron

Catalysed by CYP21A2

Reaction pageLeft to rightBalance undeterminable

Rhea RHEA:50308CC BY 4.0Reference data