Q8HYN0 · CP17A_PAPCY
- ProteinSteroid 17-alpha-hydroxylase/17,20 lyase
- GeneCYP17A1
- StatusUniProtKB reviewed (Swiss-Prot)
- Amino acids508 (go to sequence)
- Protein existenceEvidence at transcript level
- Annotation score5/5
Function
function
A cytochrome P450 monooxygenase involved in corticoid and androgen biosynthesis. Catalyzes 17-alpha hydroxylation of C21 steroids, which is common for both pathways. A second oxidative step, required only for androgen synthesis, involves an acyl-carbon cleavage. The 17-alpha hydroxy intermediates, as part of adrenal glucocorticoids biosynthesis pathway, are precursors of cortisol. Hydroxylates steroid hormones, pregnenolone and progesterone to form 17-alpha hydroxy metabolites, followed by the cleavage of the C17-C20 bond to form C19 steroids, dehydroepiandrosterone (DHEA) and androstenedione. Has 16-alpha hydroxylase activity. Catalyzes 16-alpha hydroxylation of 17-alpha hydroxy pregnenolone, followed by the cleavage of the C17-C20 bond to form 16-alpha-hydroxy DHEA. Also 16-alpha hydroxylates androgens, relevant for estriol synthesis. 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).
Catalytic activity
- a C21-steroid + O2 + reduced [NADPH--hemoprotein reductase] = a 17alpha-hydroxy-C21-steroid + H+ + H2O + oxidized [NADPH--hemoprotein reductase]This reaction proceeds in the forward direction.
- 17alpha-hydroxyprogesterone + O2 + reduced [NADPH--hemoprotein reductase] = 16alpha,17alpha-dihydroxyprogesterone + H+ + H2O + oxidized [NADPH--hemoprotein reductase]This reaction proceeds in the forward direction.
- 16alpha,17alpha-dihydroxyprogesterone + O2 + reduced [NADPH--hemoprotein reductase] = 6beta,16alpha,17alpha-trihydroxyprogesterone + H+ + H2O + oxidized [NADPH--hemoprotein reductase]This reaction proceeds in the forward direction.
- 16alpha,17alpha-dihydroxypregnenolone + O2 + reduced [NADPH--hemoprotein reductase] = 3beta,16alpha-dihydroxy-androst-5-en-17-one + acetate + 2 H+ + H2O + oxidized [NADPH--hemoprotein reductase]This reaction proceeds in the forward direction.
- 3beta-hydroxyandrost-5-en-17-one + O2 + reduced [NADPH--hemoprotein reductase] = 3beta,16alpha-dihydroxy-androst-5-en-17-one + H+ + H2O + oxidized [NADPH--hemoprotein reductase]This reaction proceeds in the forward direction.
- androst-4-ene-3,17-dione + O2 + reduced [NADPH--hemoprotein reductase] = 16alpha-hydroxyandrost-4-ene-3,17-dione + H+ + H2O + oxidized [NADPH--hemoprotein reductase]This reaction proceeds in the forward direction.
Cofactor
Activity regulation
Regulated predominantly by intracellular cAMP levels. The 17,20-lyase activity is stimulated by cytochrome b5, which acts as an allosteric effector increasing the Vmax of the lyase activity.
Pathway
Steroid hormone biosynthesis.
Steroid biosynthesis; glucocorticoid biosynthesis.
Features
Showing features for binding site.
GO annotations
Aspect | Term | |
---|---|---|
Cellular Component | endoplasmic reticulum membrane | |
Molecular Function | heme binding | |
Molecular Function | iron ion binding | |
Molecular Function | lyase activity | |
Molecular Function | steroid 17-alpha-monooxygenase activity | |
Biological Process | glucocorticoid biosynthetic process | |
Biological Process | hormone biosynthetic process | |
Biological Process | progesterone metabolic process | |
Biological Process | steroid metabolic process |
Keywords
- Molecular function
- Biological process
- Ligand
Enzyme and pathway databases
Names & Taxonomy
Protein names
- Recommended nameSteroid 17-alpha-hydroxylase/17,20 lyase
- EC number
- Alternative names
Gene names
Organism names
- Taxonomic lineageEukaryota > Metazoa > Chordata > Craniata > Vertebrata > Euteleostomi > Mammalia > Eutheria > Euarchontoglires > Primates > Haplorrhini > Catarrhini > Cercopithecidae > Cercopithecinae > Papio
Accessions
- Primary accessionQ8HYN0
Subcellular Location
UniProt Annotation
GO Annotation
Keywords
- Cellular component
PTM/Processing
Features
Showing features for chain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Chain | PRO_0000051937 | 1-508 | Steroid 17-alpha-hydroxylase/17,20 lyase | |||
Sequence: MWELVALLLLTLAYLFWPKRRCPGAKYPKSLLSLPLVGSLPFLPRHGHMHNNFFKLQKKYGPIYSVRMGTKTTVIVGHHQLAKEVLIKKGKDFSGRPQVTTLDILSNNRKGIAFADYGAHWQLHRRLAMATFALFKDGDQKLEKIICQEISTLCDMLATHNGQTIDISFPVFVAITNVISLICFNISYKNGDPELKIVHNYNEGIIDSLGKESLVDLFPWLKVFPNKTLEKLKRHVKTRNDLLTKIFENYKEKFRSDSITNMLDVLMQAKMNSDNGNAGPDQDSELLSDNHILTTIGDIFGAGVETTTSVVKWIVAFLLHNPQVKKKLYEEIDQNVGFSRTPTISDRNRLLLLEATIREVLRIRPVAPMLIPHKANVDSSIGEFAVDKGTHVIINLWALHHNEKEWHQPDQFMPERFLNPAGTQLISPSLSYLPFGAGPRSCIGEILARQELFLIMAWLLQRFDLEVPDDGQLPSLEGNPKVVFLIDSFKVKIKVRQAWREAQAEGST |
Structure
Sequence
- Sequence statusComplete
- Length508
- Mass (Da)57,638
- Last updated2003-03-01 v1
- Checksum92DEEDDF813F7263