Reaction participants Show >> << Hide
- Name help_outline a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol) Identifier CHEBI:57880 Charge -1 Formula C11H16O13PR2 SMILEShelp_outline [C@@H]1([C@@H]([C@@H]([C@@H]([C@H]([C@@H]1O)O)O)O)OP(OC[C@@H](COC(=O)*)OC(=O)*)(=O)[O-])O 2D coordinates Mol file for the small molecule Search links Involved in 74 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline an N-(2-hydroxy-very-long-chain fatty acyl)-(R)-4-hydroxysphingoid base Identifier CHEBI:155929 Charge 0 Formula C6H11NO5R2 SMILEShelp_outline [C@@H]([C@H](CO)NC(C(*)O)=O)(O)[C@@H](*)O 2D coordinates Mol file for the small molecule Search links Involved in 3 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline a 1,2-diacyl-sn-glycerol Identifier CHEBI:17815 Charge 0 Formula C5H6O5R2 SMILEShelp_outline OC[C@@H](COC([*])=O)OC([*])=O 2D coordinates Mol file for the small molecule Search links Involved in 197 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline an inositol-1-phospho-N-(2-hydroxy-very-long-chain fatty acyl)-4R-hydroxysphingoid base Identifier CHEBI:144720 Charge -1 Formula C12H21NO13PR2 SMILEShelp_outline [C@@H]([C@H](COP(=O)(O[C@H]1[C@@H]([C@H]([C@@H]([C@H]([C@H]1O)O)O)O)O)[O-])NC(C(*)O)=O)(O)[C@@H](*)O 2D coordinates Mol file for the small molecule Search links Involved in 5 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:64592 | RHEA:64593 | RHEA:64594 | RHEA:64595 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Related reactions help_outline
Specific form(s) of this reaction
Publications
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Kei1: a novel subunit of inositolphosphorylceramide synthase, essential for its enzyme activity and Golgi localization.
Sato K., Noda Y., Yoda K.
Fungal sphingolipids have inositol-phosphate head groups, which are essential for the viability of cells. These head groups are added by inositol phosphorylceramide (IPC) synthase, and AUR1 has been thought to encode this enzyme. Here, we show that an essential protein encoded by KEI1 is a novel s ... >> More
Fungal sphingolipids have inositol-phosphate head groups, which are essential for the viability of cells. These head groups are added by inositol phosphorylceramide (IPC) synthase, and AUR1 has been thought to encode this enzyme. Here, we show that an essential protein encoded by KEI1 is a novel subunit of IPC synthase of Saccharomyces cerevisiae. We find that Kei1 is localized in the medial-Golgi and that Kei1 is cleaved by Kex2, a late Golgi processing endopeptidase; therefore, it recycles between the medial- and late Golgi compartments. The growth defect of kei1-1, a temperature-sensitive mutant, is effectively suppressed by the overexpression of AUR1, and Aur1 and Kei1 proteins form a complex in vivo. The kei1-1 mutant is hypersensitive to aureobasidin A, a specific inhibitor of IPC synthesis, and the IPC synthase activity in the mutant membranes is thermolabile. A part of Aur1 is missorted to the vacuole in kei1-1 cells. We show that the amino acid substitution in kei1-1 causes release of Kei1 during immunoprecipitation of Aur1 and that Aur1 without Kei1 has hardly detectable IPC synthase activity. From these results, we conclude that Kei1 is essential for both the activity and the Golgi localization of IPC synthase. << Less
Mol. Biol. Cell 20:4444-4457(2009) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.
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Inositol phosphorylceramide synthase is located in the Golgi apparatus of Saccharomyces cerevisiae.
Levine T.P., Wiggins C.A., Munro S.
The plasma membrane of eukaryotic cells differs in lipid composition from most of the internal organelles, presumably reflecting differences in many of its functions. In particular, the plasma membrane is rich in sphingolipids and sterols, one property of which is to decrease the permeability and ... >> More
The plasma membrane of eukaryotic cells differs in lipid composition from most of the internal organelles, presumably reflecting differences in many of its functions. In particular, the plasma membrane is rich in sphingolipids and sterols, one property of which is to decrease the permeability and increase the thickness of lipid bilayers. In this paper, we examine the length of transmembrane domains throughout the yeast secretory pathway. Although the transmembrane domains of cis and medial Golgi residents are similar to those of endoplasmic reticulum proteins, these domains lengthen substantially beyond the medial Golgi, suggesting a thickening of the bilayer. Yeast sphingolipids have particularly long acyl chains, and Aur1p, the inositol phosphorylceramide synthase that initiates yeast sphingolipid synthesis, was found to be located in the Golgi apparatus by both immunofluorescence and membrane fractionation, with its active site apparently in the Golgi lumen. Thus, it appears that sphingolipid synthesis in yeast takes place in the Golgi, separated from glycerophospholipid synthesis in the endoplasmic reticulum. A similar separation has been found in mammalian cells, and this conservation suggests that such an arrangement of enzymes within the secretory pathway could be important for the creation of bilayers of different thickness within the cell. << Less
Mol. Biol. Cell 11:2267-2281(2000) [PubMed] [EuropePMC]
This publication is cited by 2 other entries.
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Sphingolipid synthesis as a target for antifungal drugs. Complementation of the inositol phosphorylceramide synthase defect in a mutant strain of Saccharomyces cerevisiae by the AUR1 gene.
Nagiec M.M., Nagiec E.E., Baltisberger J.A., Wells G.B., Lester R.L., Dickson R.C.
We have identified a Saccharomyces cerevisiae gene necessary for the step in sphingolipid synthesis in which inositol phosphate is added to ceramide to form inositol-P-ceramide, a reaction catalyzed by phosphatidylinositol:ceramide phosphoinositol transferase (IPC synthase). This step should be an ... >> More
We have identified a Saccharomyces cerevisiae gene necessary for the step in sphingolipid synthesis in which inositol phosphate is added to ceramide to form inositol-P-ceramide, a reaction catalyzed by phosphatidylinositol:ceramide phosphoinositol transferase (IPC synthase). This step should be an effective target for antifungal drugs. A key element in our experiments was the development of a procedure for isolating mutants defective in steps in sphingolipid synthesis downstream from the first step including a mutant defective in IPC synthase. An IPC synthase defect is supported by data showing a failure of the mutant strain to incorporate radioactive inositol or N-acetylsphinganine into sphingolipids and, by using an improved assay, a demonstration that the mutant strain lacks enzyme activity. Furthermore, the mutant accumulates ceramide when fed exogenous phytosphingosine as expected for a strain lacking IPC synthase activity. Ceramide accumulation is accompanied by cell death, suggesting the presence of a ceramide-activated death response in yeast. A gene, AUR1 (YKL004w), that complements the IPC synthase defect and restores enzyme activity and sphingolipid synthesis was isolated. Mutations in AUR1 had been shown previously to give resistance to the antifungal drug aureobasidin A, leading us to predict that the drug should inhibit IPC synthase activity. Our data show that the drug is a potent inhibitor of IPC synthase with an IC50 of about 0.2 nM. Fungal pathogens are an increasing threat to human health. Now that IPC synthase has been shown to be the target for aureobasidin A, it should be possible to develop high throughput screens to identify new inhibitors of IPC synthase to combat fungal diseases. << Less
J. Biol. Chem. 272:9809-9817(1997) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.