EC 2 - Transferases
EC 2.5 - Transferring alkyl or aryl groups, other than methyl groups
EC 2.5.1 - Transferring alkyl or aryl groups, other than methyl groups
EC 2.5.1.21 - Squalene synthase
IntEnz view
ENZYME view
IntEnz Enzyme Nomenclature
EC 2.5.1.21
Names
Accepted name:
squalene synthase
Other
names:
farnesyltransferase
presqualene synthase
presqualene-diphosphate synthase
farnesyl-diphosphate farnesyltransferase
squalene synthetase
SQS
presqualene synthase
presqualene-diphosphate synthase
farnesyl-diphosphate farnesyltransferase
squalene synthetase
SQS
Systematic name:
farnesyl-diphosphate:farnesyl-diphosphate farnesyltransferase
Reactions
- (1) 2 farnesyl diphosphate + NAD(P)H + H+ = squalene + 2 diphosphate + NAD(P)+
- (1a) 2 farnesyl diphosphate = diphosphate + presqualene diphosphate
- (1b) presqualene diphosphate + NAD(P)H + H+ = squalene + diphosphate + NAD(P)+
Cofactor
Comments:
This microsomal enzyme catalyses the first committed step in the biosynthesis of sterols. The enzyme from yeast requires either Mg2+ or Mn2+ for activity. 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) [8]. High concentrations of FPP inhibit the production of squalene but not of PSPP [8].
Links to other databases
Enzymes and pathways:
NC-IUBMB
,
BRENDA
,
DIAGRAM
,
ExplorEnz
,
ENZYME@ExPASy
,
KEGG
,
MetaCyc
,
UniPathway
Protein domains and families:
PROSITE:PDOC00802
Gene Ontology:
GO:0004310
,
GO:0051996
CAS Registry Number:
9077-14-9
References
-
Squalene synthetase. Solubilization and partial purification of squalene synthetase, copurification of presqualene pyrophosphate and squalene synthetase activities.J. Biol. Chem. 262 : 1505-1509 (1987). [PMID: 3805037]
-
Isoprenoid biosynthesis in rat liver peroxisomes. Characterization of cis-prenyltransferase and squalene synthetase.J. Biol. Chem. 267 : 18708-18714 (1992). [PMID: 1527001]
-
Structure and regulation of mammalian squalene synthase.Biochim. Biophys. Acta 1529 : 49-62 (2001). [PMID: 11111077]
-
Overexpression, purification, and kinetic characterization of a carboxyl-terminal-truncated yeast squalene synthetase.Arch. Biochem. Biophys. 307 : 193-199 (1993). [PMID: 8239656]
-
Solubilization, purification, and characterization of a truncated form of rat hepatic squalene synthetase.J. Biol. Chem. 267 : 8628-8635 (1992). [PMID: 1569107]
-
Squalene synthetase. Stoichiometry and kinetics of presqualene pyrophosphate and squalene synthesis by yeast microsomes.J. Biol. Chem. 253 : 4566-4573 (1978). [PMID: 26684]
-
Crystal structure of human squalene synthase. A key enzyme in cholesterol biosynthesis.J. Biol. Chem. 275 : 30610-30617 (2000). [PMID: 10896663]
-
Squalene synthase: steady-state, pre-steady-state, and isotope-trapping studies.Biochemistry 39 : 1748-1760 (2000). [PMID: 10677224]
[EC 2.5.1.21 created 1976, modified 2005]