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UniProt functional annotation for P37268 | ||
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| UniProt code: P37268. |
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| Organism: | |
Homo sapiens (Human). |
| Taxonomy: | |
Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo. |
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| Function: | |
Catalyzes the condensation of 2 farnesyl pyrophosphate (FPP) moieties to form squalene. Proceeds in two distinct steps. In the first half-reaction, two molecules of FPP react to form the stable presqualene diphosphate intermediate (PSQPP), with concomitant release of a proton and a molecule of inorganic diphosphate. In the second half-reaction, PSQPP undergoes heterolysis, isomerization, and reduction with NADPH or NADH to form squalene. It is the first committed enzyme of the sterol biosynthesis pathway. {ECO:0000269|PubMed:10896663, ECO:0000269|PubMed:24531458}. |
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| Catalytic activity: | |
Reaction=2 (2E,6E)-farnesyl diphosphate + H(+) + NADPH = 2 diphosphate + NADP(+) + squalene; Xref=Rhea:RHEA:32295, ChEBI:CHEBI:15378, ChEBI:CHEBI:15440, ChEBI:CHEBI:33019, ChEBI:CHEBI:57783, ChEBI:CHEBI:58349, ChEBI:CHEBI:175763; EC=2.5.1.21; Evidence={ECO:0000269|PubMed:10896663}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:32296; Evidence={ECO:0000305|PubMed:10896663}; |
| Catalytic activity: | |
Reaction=2 (2E,6E)-farnesyl diphosphate + H(+) + NADH = 2 diphosphate + NAD(+) + squalene; Xref=Rhea:RHEA:32299, ChEBI:CHEBI:15378, ChEBI:CHEBI:15440, ChEBI:CHEBI:33019, ChEBI:CHEBI:57540, ChEBI:CHEBI:57945, ChEBI:CHEBI:175763; EC=2.5.1.21; Evidence={ECO:0000269|PubMed:10896663}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:32300; Evidence={ECO:0000305|PubMed:10896663}; |
| Catalytic activity: | |
Reaction=2 (2E,6E)-farnesyl diphosphate = diphosphate + presqualene diphosphate; Xref=Rhea:RHEA:22672, ChEBI:CHEBI:33019, ChEBI:CHEBI:57310, ChEBI:CHEBI:175763; Evidence={ECO:0000269|PubMed:10896663, ECO:0000269|PubMed:24531458}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:22673; Evidence={ECO:0000305|PubMed:24531458}; |
| Catalytic activity: | |
Reaction=H(+) + NADH + presqualene diphosphate = diphosphate + NAD(+) + squalene; Xref=Rhea:RHEA:22228, ChEBI:CHEBI:15378, ChEBI:CHEBI:15440, ChEBI:CHEBI:33019, ChEBI:CHEBI:57310, ChEBI:CHEBI:57540, ChEBI:CHEBI:57945; Evidence={ECO:0000269|PubMed:10896663, ECO:0000269|PubMed:24531458}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:22229; Evidence={ECO:0000305|PubMed:24531458}; |
| Catalytic activity: | |
Reaction=H(+) + NADPH + presqualene diphosphate = diphosphate + NADP(+) + squalene; Xref=Rhea:RHEA:22232, ChEBI:CHEBI:15378, ChEBI:CHEBI:15440, ChEBI:CHEBI:33019, ChEBI:CHEBI:57310, ChEBI:CHEBI:57783, ChEBI:CHEBI:58349; Evidence={ECO:0000269|PubMed:10896663, ECO:0000269|PubMed:24531458}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:22233; Evidence={ECO:0000305|PubMed:24531458}; |
| Cofactor: | |
Name=Mg(2+); Xref=ChEBI:CHEBI:18420; Evidence={ECO:0000269|PubMed:24531458}; |
| Pathway: | |
Terpene metabolism; lanosterol biosynthesis; lanosterol from farnesyl diphosphate: step 1/3. {ECO:0000305}. |
| Subcellular location: | |
Endoplasmic reticulum membrane {ECO:0000250|UniProtKB:Q02769}; Multi-pass membrane protein {ECO:0000255}. |
| Tissue specificity: | |
Widely expressed. {ECO:0000269|PubMed:29909962}. |
| Disease: | |
Squalene synthase deficiency (SQSD) [MIM:618156]: An autosomal recessive disorder characterized by profound developmental delay, brain abnormalities, 2/3 syndactyly of the toes, facial dysmorphisms, low total and LDL-cholesterol, and abnormal urine organic acids. {ECO:0000269|PubMed:29909962}. Note=The disease is caused by variants affecting the gene represented in this entry. |
| Similarity: | |
Belongs to the phytoene/squalene synthase family. {ECO:0000305}. |
Annotations taken from UniProtKB at the EBI.