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Information on EC 2.5.1.21 - squalene synthase and Organism(s) Arabidopsis thaliana and UniProt Accession P53799
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2.5.1.21 squalene synthaseIUBMB 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) . High concentrations of FPP inhibit the production of squalene but not of PSPP .
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Word Map
- 2.5.1.21
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farnesylation
- cholesterol
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prenylation
- sterol
- ftase
- mevalonate
-
geranylgeranylation
-
isoprenoids
- leukemia
-
geranylgeranyltransferase
- pyrophosphate
- tipifarnib
- hmg-coa
- statin
- h-ras
-
peptidomimetic
-
epoxidase
- prenyltransferase
- dolichols
- rhob
-
isoprenylation
-
triterpene
- farnesol
-
3-hydroxy-3-methylglutaryl
- lamins
- ergosterol
-
cholesterol-lowering
- hmgcr
-
prelamin
-
p21ras
- lovastatin
-
hutchinson-gilford
- lanosterol
- manumycin
-
triterpenoids
- synthesis
-
progerin
-
farnesylpyrophosphate
- cis-prenyltransferase
- drug development
- oxidosqualene
-
ras-transformed
- medicine
-
ras-dependent
-
nonsterols
-
ras-mediated
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withanolides
- srebp-2
-
ganoderic
- agriculture
- geranylgeraniol
- industry
- cycloartenol
-
non-thiol
- 2,3-oxidosqualene
The taxonomic range for the selected organisms is: Arabidopsis thaliana
The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
Reaction Schemes
hide(Overall reactions are displayed. Show all >>)
Synonyms
farnesyltransferase, squalene synthase, sqs, fdft1, squalene synthetase, farnesyl-diphosphate farnesyltransferase, sgsqs, ssase, sqase, tksqs1, 
more
topSYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
farnesyl-diphosphate farnesyltransferase
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farnesyldiphosphate:farnesyldiphosphate farnesyltransferase
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farnesyltransferase
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presqualene synthase
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presqualene-diphosphate synthase
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squalene synthase
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squalene synthetase
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synthase, squalene
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
2 (2E,6E)-farnesyl diphosphate + NAD(P)H + H+ = squalene + 2 diphosphate + NAD(P)+
enzyme also catalyses the reduction of presqualene diphosphate by NADPH to squalene
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REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
alkenyl group transfer
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PATHWAY SOURCE
PATHWAYS
BRENDA
SYSTEMATIC NAME
IUBMB Comments
(2E,6E)-farnesyl-diphosphate:(2E,6E)-farnesyl-diphosphate farnesyltransferase
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].
CAS REGISTRY NUMBER
COMMENTARY
9077-14-9
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
isoform Sqs1. Sqs1 is the only functional squalene synthase in Arabidopsis thaliana. Isoform Sqs2 has no squalene synthase activity
UniProt
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
additional information
additional information
O23118
isoform Sqs1 is widely expressed in all tissues throughout plant development
additional information
isoform Sqs1 is widely expressed in all tissues throughout plant development
additional information
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isoform Sqs1 is widely expressed in all tissues throughout plant development
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
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squalene synthase consists of both an N-terminal catalytic domain and a C-terminal domain tethering the enzyme to the endoplasmic reticulum membrane
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
metabolism
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squalene synthase catalyzes the first committed step in sterol biosynthesis
UNIPROT
ENTRY NAME
ORGANISM
NO. OF AA
NO. OF TRANSM. HELICES
MOLECULAR WEIGHT[Da]
SOURCE
SEQUENCE
LOCALIZATION PREDICTION
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable).
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable). FDFT1_ARATH
410
1
47142
Swiss-Prot
other Location (Reliability: 2)
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
additional information
-
squalene synthase consists of both an N-terminal catalytic domain and a C-terminal domain tethering the enzyme to the endoplasmic reticulum membrane
PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
additional information
additional information
O23118
expression as fusion protein after replacement of the 69 C-terminal residues of SQS2 by the111 C-terminal residues of the Schizosaccharomyces pombe. Like wild-type, the fusion protein has no catalytic activity
additional information
expression as fusion protein after replacement of the 69 C-terminal residues of SQS2 by the111 C-terminal residues of the Schizosaccharomyces pombe. Like wild-type, the fusion protein has no catalytic activity
additional information
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expression as fusion protein after replacement of the 69 C-terminal residues of SQS2 by the111 C-terminal residues of the Schizosaccharomyces pombe. Like wild-type, the fusion protein has no catalytic activity
CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
expression as green fluorescent protein-tagged version in onion
O23118, P53799
gene SQS, recombinant enzyme expression in an enzyme-deficient SQS-knockout Saccharomyces cerevisiae DELTAerg9 strain, the enzyme can partially complement the knockout mutation when the gene is weakly expressed, but when highly expressed, the non-fungal squalene synthase cannot complement the yeast mutation and instead leads to the accumulation of a toxic intermediate(s) as defined by mutations of genes downstream in the ergosterol pathway
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REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Nakashima, T.; Inoue, T.; Oka, A.; Nishino, T.; Osumi, T.; Hata, S.
Cloning, expression, and characterization of cDNAs encoding Arabidopsis thaliana squalene synthase
Proc. Natl. Acad. Sci. USA
92
2328-2332
1995
Arabidopsis thaliana
Busquets, A.; Keim, V.; Closa, M.; del Arco, A.; Boronat, A.; Arro, M.; Ferrer, A.
Arabidopsis thaliana contains a single gene encoding squalene synthase
Plant Mol. Biol.
67
25-36
2008
Arabidopsis thaliana (O23118), Arabidopsis thaliana (P53799), Arabidopsis thaliana
Linscott, K.B.; Niehaus, T.D.; Zhuang, X.; Bell, S.A.; Chappell, J.
Mapping a kingdom-specific functional domain of squalene synthase
Biochim. Biophys. Acta
1861
1049-1057
2016
Arabidopsis thaliana, Homo sapiens (P37268), Saccharomyces cerevisiae (P53866), Saccharomyces cerevisiae, Botryococcus braunii (Q9SDW9)
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