TRAPP is a conserved protein complex required early in the secretory pathway. Here, we report two forms of TRAPP, TRAPP I and TRAPP II, that mediate different transport events. Using chemically pure TRAPP I and COPII vesicles, we have reconstituted vesicle targeting in vitro. The binding of COPII vesicles to TRAPP I is specific, blocked by GTPγS, and, surprisingly, does not require other tethering factors. Our findings imply that TRAPP I is the receptor on the Golgi for COPII vesicles. Once the vesicle binds to TRAPP I, the small GTP binding protein Ypt1p is activated and other tethering factors are recruited.
Sacher, M., Barrowman, J., Wang, W., Horecka, J., Zhang, Y., Pypaert, M., & Ferro-Novick, S. (2001). TRAPP I implicated in the specificity of tethering in ER-to-Golgi transport. Molecular Cell, 7(2), 433–442. https://doi.org/10.1016/S1097-2765(01)00190-3