| EC |
2.4.1.370 |
| Accepted name: |
inositol phosphorylceramide mannosyltransferase |
| Reaction: |
GDP-α-D-mannose + a (4R)-4-hydroxy-N-[(2R)-2-hydroxy-very-long-chain-acyl]-1-O-[(1D-myo-inositol-1-O-yl)hydroxyphosphoryl]sphinganine = a (4R)-4-hydroxy-N-[(2R)-2-hydroxy-very-long-chain-acyl]-1-O-{[6-O-(α-D-mannosyl)-1D-myo-inositol-1-O-yl]hydroxyphosphoryl}sphinganine + GDP |
| Glossary: |
a (4R)-4-hydroxy-N-[(2R)-2-hydroxy-very-long-chain-acyl]-1-O-[(1D-myo-inositol-1-O-yl)hydroxyphosphoryl]sphinganine = a very-long-chain inositol phospho-α hydroxyphytoceramide = IPC
a (4R)-4-hydroxy-N-[(2R)-2-hydroxy-very-long-chain-acyl]-1-O-{[6-O-(α-D-mannosyl)-1D-myo-inositol-1-O-yl]hydroxyphosphoryl}sphinganine = a very-long-chain mannosylinositol phospho-α-hydroxyphytoceramide = MIPC |
| Other name(s): |
SUR1 (gene name); CSH1 (gene name) |
| Systematic name: |
GDP-α-D-mannose:(4R)-4-hydroxy-N-[(2R)-2-hydroxy-very-long-chain-acyl]-1-O-[(1D-myo-inositol-1-O-yl)hydroxyphosphoryl]sphinganine mannosyltransferase (configuration-retaining) |
| Comments: |
The simplest complex sphingolipid of yeast, inositol-phospho-α-hydroxyphytoceramide (IPC), is usually mannosylated to yield mannosyl-inositol-phospho-α hydroxyphytoceramide (MIPC). The enzyme is located in the Golgi apparatus, and utilizes GDP-mannose as the mannosyl group donor. It consists of a catalytic subunit (SUR1 or CSH1) and a regulatory subunit (CSG2). |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc |
| References: |
| 1. |
Beeler, T.J., Fu, D., Rivera, J., Monaghan, E., Gable, K. and Dunn, T.M. SUR1 (CSG1/BCL21), a gene necessary for growth of Saccharomyces cerevisiae in the presence of high Ca2+ concentrations at 37 degrees C, is required for mannosylation of inositolphosphorylceramide. Mol. Gen. Genet. 255 (1997) 570–579. [DOI] [PMID: 9323360] |
| 2. |
Dean, N., Zhang, Y.B. and Poster, J.B. The VRG4 gene is required for GDP-mannose transport into the lumen of the Golgi in the yeast, Saccharomyces cerevisiae. J. Biol. Chem. 272 (1997) 31908–31914. [DOI] [PMID: 9395539] |
| 3. |
Uemura, S., Kihara, A., Inokuchi, J. and Igarashi, Y. Csg1p and newly identified Csh1p function in mannosylinositol phosphorylceramide synthesis by interacting with Csg2p. J. Biol. Chem. 278 (2003) 45049–45055. [DOI] [PMID: 12954640] |
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| [EC 2.4.1.370 created 2019] |
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| EC |
2.7.1.227 |
| Accepted name: |
inositol phosphorylceramide synthase |
| Reaction: |
1-phosphatidyl-1D-myo-inositol + a very-long-chain (2′R)-2′-hydroxy-phytoceramide = 1,2-diacyl-sn-glycerol + a (4R)-4-hydroxy-N-[(2R)-2-hydroxy-very-long-chain-acyl]-1-O-[(1D-myo-inositol-1-O-yl)hydroxyphosphoryl]sphinganine |
| Glossary: |
a (4R)-4-hydroxy-N-[(2R)-2-hydroxy-very-long-chain-acyl]-1-O-[(1D-myo-inositol-1-O-yl)hydroxyphosphoryl]sphinganine = a very-long-chain inositol phospho-α hydroxyphytoceramide = IPC |
| Other name(s): |
AUR1 (gene name); KEI1 (gene name) |
| Systematic name: |
1-phosphatidyl-1D-myo-inositol:a very-long-chain (2′R)-2′-hydroxy-phytoceramide phosphoinositoltransferase |
| Comments: |
The enzyme, characterized from yeast, attaches a phosphoinositol headgroup to α-hydroxyphytoceramides, generating a very-long-chain inositol phospho-α hydroxyphytoceramide (IPC), the simplest of the three complex sphingolipids produced by yeast. |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc |
| References: |
| 1. |
Nagiec, M.M., Nagiec, E.E., Baltisberger, J.A., Wells, G.B., Lester, R.L. and Dickson, R.C. 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. J. Biol. Chem. 272 (1997) 9809–9817. [PMID: 9092515] |
| 2. |
Levine, T.P., Wiggins, C.A. and Munro, S. Inositol phosphorylceramide synthase is located in the Golgi apparatus of Saccharomyces cerevisiae. Mol. Biol. Cell 11 (2000) 2267–2281. [PMID: 10888667] |
| 3. |
Sato, K., Noda, Y. and Yoda, K. Kei1: a novel subunit of inositolphosphorylceramide synthase, essential for its enzyme activity and Golgi localization. Mol. Biol. Cell 20 (2009) 4444–4457. [PMID: 19726565] |
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| [EC 2.7.1.227 created 2019] |
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