Exiting the Endoplasmic Reticulum

Vesicular transport from the endoplasmic reticulum (ER) to the Golgi complex constitutes the initial step in protein secretion. COPII‐coated vesicles mediate the export of newly synthesized proteins from the ER, and this transport step is coupled with COPI‐mediated retrograde traffic to form a transport circuit that supports the compositional asymmetry of the ER–Golgi system. Biochemical and structural studies have advanced our understanding of the mechanisms that control vesicle formation and cargo–protein capture. Recent work has highlighted the function of transitional ER regions in specifying the location of COPII budding.