IUBMB Enzyme Nomenclature


Accepted name: inositol phosphorylceramide mannosyltransferase

Reaction: GDP-α-D-mannose + a very-long-chain inositol phospho-(2'R)-2'-hydroxyphytoceramide = a very-long-chain mannosylinositol phospho-(2'R)-2'-hydroxyphytoceramide + GDP

Glossary: a very-long-chain mannosylinositol phospho-(2'R)-2'-hydroxyphytoceramide = a very-long-chain mannosylinositol phospho-α-hydroxyphytoceramide = MIPC

Other name(s): SUR1 (gene name); CSH1 (gene name)

Systematic name: GDP-α-D-mannose:inositol phospho-(2'R)-2'-hydroxyphytoceramide mannosyltransferase

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, CAS registry number:


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. [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. [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. [PMID: 12954640]

[EC created 2019]

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