title: Diacylglycerol kinase delta suppresses ER-to-Golgi traffic via its SAM and PH domains.
abstract: We report here that the anterograde transport from the endoplasmic reticulum (ER) to the Golgi was markedly suppressed by diacylglycerol kinase delta (DGKdelta) that uniquely possesses a pleckstrin homology (PH) and a sterile alpha motif (SAM) domain. A low-level expression of DGKdelta in NIH3T3 cells caused redistribution into the ER of the marker proteins of the Golgi membranes and the vesicular-tubular clusters (VTCs). In this case DGKdelta delayed the ER-to-Golgi traffic of vesicular stomatitis virus glycoprotein (VSV G) and also the reassembly of the Golgi apparatus after brefeldin A (BFA) treatment and washout. DGKdelta was demonstrated to associate with the ER through its C-terminal SAM domain acting as an ER-targeting motif. Both of the SAM domain and the N-terminal PH domain of DGKdelta were needed to exert its effects on ER-to-Golgi traffic. Kinase-dead mutants of DGKdelta were also effective as the wild-type enzyme, suggesting that the catalytic activity of DGK was not involved in the present observation. Remarkably, the expression of DGKdelta abrogated formation of COPII-coated structures labeled with Sec13p without affecting COPI structures. These findings indicate that DGKdelta negatively regulates ER-to-Golgi traffic by selectively inhibiting the formation of ER export sites without significantly affecting retrograde transport.
authors.affiliation: Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan.
authors.forename: Hisao
authors.initials: H
authors.lastname: Nagaya
authors.forename: Ikuo
authors.initials: I
authors.lastname: Wada
authors.forename: Yan-Jun
authors.initials: YJ
authors.lastname: Jia
authors.forename: Hideo
authors.initials: H
authors.lastname: Kanoh
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001798:Blood Proteins / Q000737:chemistry; D020126:Brefeldin A / Q000494:pharmacology; D022181:COP-Coated Vesicles / Q000378:metabolism; D019556:COS Cells; D002460:Cell Line; D019852:Diacylglycerol Kinase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D007425:Intracellular Membranes / Q000378:metabolism; D008164:Luminescent Proteins / Q000032:analysis; D051379:Mice; D018613:Microscopy, Confocal; D008862:Microsomes, Liver / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D001798:Blood Proteins; D008164:Luminescent Proteins; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; C039077:platelet protein P47; D049452:Green Fluorescent Proteins; D020126:Brefeldin A; D019852:Diacylglycerol Kinase