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ENZYME

ENZYME entry: EC 2.5.1.21

PURL: https://purl.expasy.org/enzyme/EC/2.5.1.21
Accepted Name
squalene synthase
Alternative Name(s)
farnesyl-diphosphate farnesyltransferase
farnesyltransferase
presqualene-diphosphate synthase
presqualene synthase
squalene synthetase
Reaction catalysed
  • 2 (2E,6E)-farnesyl diphosphate + NADPH + H(+) = squalene + 2 diphosphate + NADP(+)
  • 2 (2E,6E)-farnesyl diphosphate + NADH + H(+) = squalene + 2 diphosphate + NAD(+)
Comment(s)
  • This microsomal enzyme catalyzes the first committed step in the biosynthesis of sterols.
  • In the absence of NAD(P)H, presqualene diphosphate (PSPP) is accumulated.
  • When NAD(P)H is present, presqualene diphosphate does not dissociate from the enzyme during the synthesis of squalene from farnesyl diphosphate (FPP).
  • High concentrations of FPP inhibit the production of squalene but not of PSPP.
Cross-references
Rhea expert-curated reactions2.5.1.21
ExplorEnz2.5.1.21
IUBMB Enzyme Nomenclature2.5.1.21
UniProtKB/Swiss-Prot
Q9SDW9, BSS_BOTBRA0A345BJQ0, CLZ20_COCLUQ4WAG4, ERG9_ASPFU
A0A1D8PI71, ERG9_CANALP78589, ERG9_CANAXA0SJQ5, ERG9_GANLU
V6RPN0, ERG9_GIBZEP36596, ERG9_SCHPOP29704, ERG9_YEAST
P53799, FDFT1_ARATHQ32KR6, FDFT_BOVINQ9HGZ6, FDFT_CANGA
O74165, FDFT_CYBJAQ54DR1, FDFT_DICDIQ752X9, FDFT_EREGS
P37268, FDFT_HUMANP53798, FDFT_MOUSEQ92459, FDFT_MYCMD
Q7S4Z6, FDFT_NEUCRP53800, FDFT_NICBEQ5R6U3, FDFT_PONAB
Q02769, FDFT_RATQ9Y753, FDFT_YARLIA0A142ZC57, LOS_BOTBR
A0A144YEA5, LSS_BOTBRA0A3G1DJL2, MFR6_PHOSMD0VFU8, SLSS_SOLLC
A0A1P7Y0A2, SQS10_PANGIA0A1P7Y0D4, SQS11_PANGIA0A1P7Y0A8, SQS12_PANGI
A0A1P7Y0D0, SQS13_PANGIO48666, SQS1_PANGIC9E894, SQS2_PANGI
D2K762, SQS3_PANGIA0A1P7Y0C9, SQS8_PANGI
BRENDA2.5.1.21
MetaCyc2.5.1.21
KEGG Ligand Database for Enzyme Nomenclature2.5.1.21
EC2PDB2.5.1.21
MEDLINEFind literature relating to 2.5.1.21

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All ENZYME / UniProtKB/Swiss-Prot entries corresponding to 2.5.1.-
All ENZYME / UniProtKB/Swiss-Prot entries corresponding to 2.5.-.-
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