Abstract
The budding of endoplasmic reticulum (ER)-derived vesicles is dependent on the COPII coat complex. Coat assembly is initiated when Sar1-GTP recruits the cargo adaptor complex, Sec23/Sec24, by binding to its GTPase-activating protein (GAP) Sec23 (ref. 2). This leads to the capture of transmembrane cargo by Sec24 (refs 3, 4) before the coat is polymerized by the Sec13/Sec31 complex. The initial interaction of a vesicle with its target membrane is mediated by tethers. We report here that in yeast and mammalian cells the tethering complex TRAPPI (ref. 7) binds to the coat subunit Sec23. This event requires the Bet3 subunit. In vitro studies demonstrate that the interaction between Sec23 and Bet3 targets TRAPPI to COPII vesicles to mediate vesicle tethering. We propose that the binding of TRAPPI to Sec23 marks a coated vesicle for fusion with another COPII vesicle or the Golgi apparatus. An implication of these findings is that the intracellular destination of a transport vesicle may be determined in part by its coat and its associated cargo.
| Original language | English |
|---|---|
| Pages (from-to) | 941-944 |
| Number of pages | 4 |
| Journal | Nature |
| Volume | 445 |
| Issue number | 7130 |
| DOIs | |
| State | Published - Feb 22 2007 |
Funding
Acknowledgements We thank L. Walker for help in the preparation of the manuscript, Y. Zhang, and K. Mullen for technical assistance. We also thank J. Barrowman for help with the yeast in vitro tethering assay, R. Schekman, C. Kaiser, F. Gorelick and T. Schroer for purified proteins, antibodies, plasmids and strains, and E. Miller for advice on stripping COPII coats from vesicles. This work was supported by the Howard Hughes Medical Institute. Salary support for S.F.-N., H.C., S.Y., S.M. and D.L. was also provided by the Howard Hughes Medical Institute. Work at the University of Montana was supported by an NIH grant to J.C.H. and the NIH-COBRE Center for Structural and Functional Neuroscience.
| Funders | Funder number |
|---|---|
| Howard Hughes Medical Institute | |
| R01GM080616 |