| Structural highlights
Function
[C43BP_HUMAN] Shelters ceramides and diacylglycerol lipids inside its START domain and mediates the intracellular trafficking of ceramides and diacylglycerol lipids in a non-vesicular manner.[1] [2] [3] [4]
Publication Abstract from PubMed
De novo synthesis of the sphingolipid sphingomyelin requires non-vesicular transport of ceramide from the endoplasmic reticulum to the Golgi by the multidomain protein ceramide transfer protein (CERT). CERT's N-terminal pleckstrin homology (PH) domain targets it to the Golgi by binding to phosphatidylinositol 4-phosphate (PtdIns(4)P) in the Golgi membrane, whereas its C-terminal StAR-related lipid transfer domain (START) carries out ceramide transfer. Hyperphosphorylation of a serine-rich motif immediately after the PH domain decreases both PtdIns(4)P binding and ceramide transfer by CERT. This down-regulation requires both the PH and START domains, suggesting a possible inhibitory interaction between the two domains. In this study we show that isolated PH and START domains interact with each other. The crystal structure of a PH-START complex revealed that the START domain binds to the PH domain at the same site for PtdIns(4)P-binding, suggesting that the START domain competes with PtdIns(4)P for association with the PH domain. We further report that mutations disrupting the PH-START interaction increase both PtdIns(4)P-binding affinity and ceramide transfer activity of a CERT-serine-rich phosphorylation mimic. We also found that these mutations increase the Golgi localization of CERT inside the cell, consistent with enhanced PtdIns(4)P binding of the mutant. Collectively, our structural, biochemical, and cellular investigations provide important structural insight into the regulation of CERT function and localization.
Interaction between the PH and START domains of ceramide transfer protein competes with phosphatidylinositol 4-phosphate binding by the PH domain.,Prashek J, Bouyain S, Fu M, Li Y, Berkes D, Yao X J Biol Chem. 2017 Aug 25;292(34):14217-14228. doi: 10.1074/jbc.M117.780007. Epub , 2017 Jun 26. PMID:28652409[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Hanada K, Kumagai K, Yasuda S, Miura Y, Kawano M, Fukasawa M, Nishijima M. Molecular machinery for non-vesicular trafficking of ceramide. Nature. 2003 Dec 18;426(6968):803-9. PMID:14685229 doi:https://dx.doi.org/10.1038/nature02188
- ↑ Fugmann T, Hausser A, Schoffler P, Schmid S, Pfizenmaier K, Olayioye MA. Regulation of secretory transport by protein kinase D-mediated phosphorylation of the ceramide transfer protein. J Cell Biol. 2007 Jul 2;178(1):15-22. Epub 2007 Jun 25. PMID:17591919 doi:https://dx.doi.org/jcb.200612017
- ↑ Kudo N, Kumagai K, Tomishige N, Yamaji T, Wakatsuki S, Nishijima M, Hanada K, Kato R. Structural basis for specific lipid recognition by CERT responsible for nonvesicular trafficking of ceramide. Proc Natl Acad Sci U S A. 2008 Jan 15;105(2):488-93. Epub 2008 Jan 9. PMID:18184806
- ↑ Kudo N, Kumagai K, Matsubara R, Kobayashi S, Hanada K, Wakatsuki S, Kato R. Crystal structures of the CERT START domain with inhibitors provide insights into the mechanism of ceramide transfer. J Mol Biol. 2010 Feb 19;396(2):245-51. Epub 2009 Dec 28. PMID:20036255 doi:10.1016/j.jmb.2009.12.029
- ↑ Prashek J, Bouyain S, Fu M, Li Y, Berkes D, Yao X. Interaction between the PH and START domains of ceramide transfer protein competes with phosphatidylinositol 4-phosphate binding by the PH domain. J Biol Chem. 2017 Aug 25;292(34):14217-14228. doi: 10.1074/jbc.M117.780007. Epub , 2017 Jun 26. PMID:28652409 doi:https://dx.doi.org/10.1074/jbc.M117.780007
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