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Regulation of the transport and protein levels of the inositol phosphorylceramide mannosyltransferases Csg1 and Csh1 by the Ca2+ binding protein Csg2
| Title: | Regulation of the transport and protein levels of the inositol phosphorylceramide mannosyltransferases Csg1 and Csh1 by the Ca2+ binding protein Csg2 |
| Authors: | Uemura, Satoshi Browse this author | | Kihara, Akio Browse this author →KAKEN DB | | Iwaki, Soichiro Browse this author | | Inokuchi, Jin-ichi Browse this author | | Igarashi, Yasuyuki Browse this author →KAKEN DB |
| Issue Date: | 23-Mar-2007 |
| Publisher: | American Society for Biochemistry and Molecular Biology |
| Journal Title: | Journal of Biological Chemistry |
| Volume: | 282 |
| Issue: | 12 |
| Start Page: | 8613 |
| End Page: | 8621 |
| Publisher DOI: | 10.1074/jbc.M606649200 |
| PMID: | 17220303 |
| Abstract: | Complex sphingolipids in yeast are known to function in cellular adaptation to environmental changes. One of the yeast complex sphingolipids, mannosylinositol phosphorylceramide (MIPC), is produced by the redundant inositol phosphorylceramide (IPC) mannosyltransferases Csg1 and Csh1. The Ca2+-binding protein Csg2 can form a complex with either Csg1 or Csh1 and is considered to act as a regulatory subunit. However, the role of Csg2 in MIPC synthesis has remained unclear. In this study, we found that Csg1 and Csh1 are N-glycosylated with core-type and mannan-type structures, respectively. Further identification of the glycosylated residues suggests that both Csg1 and Csh1 exhibit membrane topology with their C termini in the cytosol and their mannosyltransferase domains in the lumen. After complexing with Csg2, both Csg1 and Csh1 function in the Golgi, and then are delivered to the vacuole for degradation. However, uncomplexed Csh1 cannot exit from the endoplasmic reticulum. We also demonstrated that Ca2+ stimulates IPC-to-MIPC conversion, because of a Csg2-dependent increase in Csg1 levels. Thus, Csg2 has several regulatory functions for Csg1 and Csh1, including stability, transport, and gene expression. |
| Rights: | Copyright © 2007 by the American Society for Biochemistry and Molecular Biology |
| Type: | article (author version) |
| URI: | http://hdl.handle.net/2115/22536 |
| Appears in Collections: | 薬学研究院 (Faculty of Pharmaceutical Sciences) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 木原 章雄
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