Diacylglycerol Kinase δ Suppresses ER-to-Golgi Traffic via Its SAM and PH Domains
- Randy W. Schekman, Monitoring Editor
- Submitted May 21, 2001.
- Revised October 17, 2001.
- Accepted October 31, 2001.
Abstract
We report here that the anterograde transport from the endoplasmic reticulum (ER) to the Golgi was markedly suppressed by diacylglycerol kinase δ (DGKδ) that uniquely possesses a pleckstrin homology (PH) and a sterile α motif (SAM) domain. A low-level expression of DGKδ 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 DGKδ 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. DGKδ 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 DGKδ were needed to exert its effects on ER-to-Golgi traffic. Kinase-dead mutants of DGKδ 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 DGKδ abrogated formation of COPII-coated structures labeled with Sec13p without affecting COPI structures. These findings indicate that DGKδ negatively regulates ER-to-Golgi traffic by selectively inhibiting the formation of ER export sites without significantly affecting retrograde transport.
Footnotes
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↵‡ Corresponding author. E-mail address:wada{at}sapmed.ac.jp.
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Article published online ahead of print. Mol. Biol. Cell 10.1091/mbc.01–05-0255. Articel and publication date are atwww.molbiolcell.org/cgi/doi/10.1091/mbc.01–05-0255.
Abbreviations used:
- BFA
- brefeldin A
- BSA
- bovine serum albumin
- CFP
- cyan fluorescent protein
- DGK
- diacylglycerol kinase
- DMEM
- Dulbecco's modified minimum essential medium
- ER
- endoplasmic reticulum
- GFP
- green fluorescent protein
- GT
- galactosyltransferase
- PBS
- phosphate-buffered saline
- PH
- pleckstrin homology
- SAM
- sterile α motif
- VSV G
- vesicular stomatitis virus glycoprotein
- VTC
- vesicular-tubular cluster
- YFP
- yellow fluorescent protein
