Q8HYN0 · CP17A_PAPCY

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.
    EC:1.14.14.19 (UniProtKB | ENZYME | Rhea)
  • O2 + progesterone + reduced [NADPH--hemoprotein reductase] = 17alpha-hydroxyprogesterone + H+ + H2O + oxidized [NADPH--hemoprotein reductase]
    This reaction proceeds in the forward direction.
    EC:1.14.14.19 (UniProtKB | ENZYME | Rhea)
  • O2 + pregnenolone + reduced [NADPH--hemoprotein reductase] = 17alpha-hydroxypregnenolone + H+ + H2O + oxidized [NADPH--hemoprotein reductase]
    This reaction proceeds in the forward direction.
    EC:1.14.14.19 (UniProtKB | ENZYME | Rhea)
  • 17alpha-hydroxyprogesterone + O2 + reduced [NADPH--hemoprotein reductase] = acetate + androst-4-ene-3,17-dione + 2 H+ + H2O + oxidized [NADPH--hemoprotein reductase]
    This reaction proceeds in the forward direction.
    EC:1.14.14.32 (UniProtKB | ENZYME | Rhea)
  • 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.
  • 17alpha-hydroxypregnenolone + O2 + reduced [NADPH--hemoprotein reductase] = 3beta-hydroxyandrost-5-en-17-one + acetate + 2 H+ + H2O + oxidized [NADPH--hemoprotein reductase]
    This reaction proceeds in the forward direction.
    EC:1.14.14.32 (UniProtKB | ENZYME | Rhea)
  • 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

heme (UniProtKB | Rhea| CHEBI:30413 )

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.

TypeIDPosition(s)Description
Binding site202substrate
Binding site442Fe (UniProtKB | ChEBI) of heme (UniProtKB | ChEBI); axial binding residue

GO annotations

AspectTerm
Cellular Componentendoplasmic reticulum membrane
Molecular Functionheme binding
Molecular Functioniron ion binding
Molecular Functionlyase activity
Molecular Functionsteroid 17-alpha-monooxygenase activity
Biological Processglucocorticoid biosynthetic process
Biological Processhormone biosynthetic process
Biological Processprogesterone metabolic process
Biological Processsteroid metabolic process

Keywords

Enzyme and pathway databases

Names & Taxonomy

Protein names

  • Recommended name
    Steroid 17-alpha-hydroxylase/17,20 lyase
  • EC number
  • Alternative names
    • 17-alpha-hydroxyprogesterone aldolase (EC:1.14.14.32
      ) . EC:1.14.14.32 (UniProtKB | ENZYME | Rhea)
    • CYPXVII
    • Cytochrome P450 17A1
    • Cytochrome P450-C17 (Cytochrome P450c17)
    • Steroid 17-alpha-monooxygenase

Gene names

    • Name
      CYP17A1
    • Synonyms
      CYP17

Organism names

  • Taxonomic identifier
  • Taxonomic lineage
    Eukaryota > Metazoa > Chordata > Craniata > Vertebrata > Euteleostomi > Mammalia > Eutheria > Euarchontoglires > Primates > Haplorrhini > Catarrhini > Cercopithecidae > Cercopithecinae > Papio

Accessions

  • Primary accession
    Q8HYN0

Subcellular Location

PTM/Processing

Features

Showing features for chain.

TypeIDPosition(s)Description
ChainPRO_00000519371-508Steroid 17-alpha-hydroxylase/17,20 lyase

Structure

Family & Domains

Sequence similarities

Belongs to the cytochrome P450 family.

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    508
  • Mass (Da)
    57,638
  • Last updated
    2003-03-01 v1
  • Checksum
    92DEEDDF813F7263
MWELVALLLLTLAYLFWPKRRCPGAKYPKSLLSLPLVGSLPFLPRHGHMHNNFFKLQKKYGPIYSVRMGTKTTVIVGHHQLAKEVLIKKGKDFSGRPQVTTLDILSNNRKGIAFADYGAHWQLHRRLAMATFALFKDGDQKLEKIICQEISTLCDMLATHNGQTIDISFPVFVAITNVISLICFNISYKNGDPELKIVHNYNEGIIDSLGKESLVDLFPWLKVFPNKTLEKLKRHVKTRNDLLTKIFENYKEKFRSDSITNMLDVLMQAKMNSDNGNAGPDQDSELLSDNHILTTIGDIFGAGVETTTSVVKWIVAFLLHNPQVKKKLYEEIDQNVGFSRTPTISDRNRLLLLEATIREVLRIRPVAPMLIPHKANVDSSIGEFAVDKGTHVIINLWALHHNEKEWHQPDQFMPERFLNPAGTQLISPSLSYLPFGAGPRSCIGEILARQELFLIMAWLLQRFDLEVPDDGQLPSLEGNPKVVFLIDSFKVKIKVRQAWREAQAEGST

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
AF458331
EMBL· GenBank· DDBJ
AAN86252.1
EMBL· GenBank· DDBJ
mRNA

Similar Proteins

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