Seeking a way out: export of proteins from the plant endoplasmic reticulum.

The functionality of the secretory pathway relies on the efficient transfer of cargo molecules from their site of synthesis in the endoplasmic reticulum (ER) to successive compartments within the pathway. Although transport mechanisms of secretory proteins have been studied in detail in various non-plant systems, it is only recently that our knowledge of secretory routes in plants has expanded dramatically. This review focuses on exciting new findings concerning the exit mechanisms of cargo proteins from the plant ER and the role of ER export sites in this process.