Abstract
Newly synthesized secretory proteins are transported from the endoplasmic reticulum (ER) to the Golgi complex in vesicles coated with COPII coat proteins. The incorporation of certain cargo molecules into the COPII vesicles is mediated by direct interaction between the cytoplasmic domain of the cargo protein and COPII coat components. The assembly and disassembly of COPII coat components on the membrane are regulated by the small GTPase Sar1p. Our recent data suggest that the Sar1p GTPase cycle plays a key role in the regulation of COPII coat dynamics and cargo sorting during vesicle formation.
