CERT mediates intermembrane transfer of various molecular species of ceramides

被引:182
作者
Kumagai, K
Yasuda, S
Okemoto, K
Nishijima, M
Kobayashi, S
Hanada, K
机构
[1] Natl Inst Infect Dis, Dept Biochem & Cell Biol, Shinjuku Ku, Tokyo 1628640, Japan
[2] Univ Tokyo, Grad Sch Pharmaceut Sci, Bunkyo Ku, Tokyo 1130033, Japan
关键词
D O I
10.1074/jbc.M409290200
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Ceramide produced at the endoplasmic reticulum is transported to the Golgi apparatus for conversion to sphingomyelin. The main pathway of endoplasmic reticulum-to-Golgi transport of ceramide is mediated by CERT, a cytosolic 68-kDa protein, in a nonvesicular manner. CERT contains a domain that catalyzes the intermembrane transfer of natural C-16-ceramide. In this study, we examined the ligand specificity of CERT in detail by using a cell-free assay system for intermembrane transfer of lipids. CERT did not mediate the transfer of sphingosine or sphingomyelin at all. The activity of CERT to transfer saturated and unsaturated diacylglycerols, which structurally resemble ceramide, was 5-10% of the activity toward C-16-ceramide. Among four stereoisomers of C-16-ceramide, CERT specifically recognized the natural D-erythro isomer. CERT efficiently transferred ceramides having C-14, C-16, C-18, and C-20 chains, but not longer acyl chains, and also mediated efficient transfer of C-16-dihydroceramide and C-16-phytoceramide. Binding assays showed that CERT also recognizes short chain fluorescent analogs of ceramide with a stoichiometry of 1:1. Moreover, (1R,3R)-N-(3-hydroxy-1-hydroxymethyl-3-phenylpropyl)dodecamide, which inhibited the CERT-dependent pathway of ceramide trafficking in intact cells, was found to be an antagonist of the CERT protein. These results indicate that CERT can mediate transfer of various types of ceramides that naturally exist and their close relatives.
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页码:6488 / 6495
页数:8
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