SRD5A3 - Polyprenol reductase - human protein (Function)
 
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References

 
SRD5A3 »  Polyprenol reductase   [ EC 1.3.1.94 ]
 
Protein also known as:  3-oxo-5-alpha-steroid 4-dehydrogenase 3 [EC 1.3.1.22].
Gene name:  SRD5A3
Entry whose protein(s) existence is based on evidence at protein level
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GENE REF ISO

Function

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Overview 
Plays a key role in early steps of protein N-linked glycosylation by being required for the conversion of polyprenol into dolichol. Dolichols are required for the synthesis of dolichol-linked monosaccharides and the oligosaccharide precursor used for N-glycosylation. Acts as a polyprenol reductase that promotes the reduction of the alpha-isoprene unit of polyprenols into dolichols in a NADP-dependent mechanism. Also able to convert testosterone (T) into 5-alpha-dihydrotestosterone (DHT).  
2
  • CuratedUniProtKB
GO molecular function 
3-oxo-5-alpha-steroid 4-dehydrogenase activitydefinition[GO:0003865]  
1
  • IDAUniProtKB
Cholestenone 5-alpha-reductase activitydefinition[GO:0047751]  
  • IEAEC 2 GO
Oxidoreductase activity, acting on the CH-CH group of donors, NAD or NADP as acceptordefinition[GO:0016628]  
1
  • IDAUniProtKB
GO biological process 
Dolichol metabolic processdefinition[GO:0019348]  
1
  • IDAUniProtKB
Dolichol-linked oligosaccharide biosynthetic processdefinition[GO:0006488]  
1
  • IMPUniProtKB
Polyprenol catabolic processdefinition[GO:0016095]  
1
  • IDAUniProtKB
Protein glycosylationdefinition[GO:0006486]  
  • IEAUniPathway
Enzymatic activity 
This protein acts as an enzyme. It is known to catalyze the following reactions
EC 1.3.1.94: Ditrans,polycis-dolichol + NADP(+) ditrans,polycis-polyprenol + NADPH.  
2
  • CuratedUniProtKB
EC 1.3.1.22: A 3-oxo-5-alpha-steroid + NADP(+) a 3-oxo-Delta(4)-steroid + NADPH.  
2
  • CuratedUniProtKB
Pathways 
This protein is involved in the following pathway
According to KEGG, this protein belongs to the following pathway:
Steroid hormone biosynthesis  hsa00140+79644  
According to Reactome, this protein belongs to the following pathways:
Metabolism  REACT_111217  
Steroid hormones  REACT_15493  
 
More information is available from:
 

Keywords

Molecular function 
Oxidoreductase  definition   [KW-0560]
Technical term 
Reference proteome  definition   [KW-1185]
 

Further external links

GeneWiki: SRD5A3
GenomeRNAi: 79644
PRO: PR:Q9H8P0