Remaking an exit: dynamic regulation of ER exit sites by post-translational modifications.

Endoplasmic reticulum exit sites (ERES) are dynamic platforms that coordinate not only protein trafficking but also protein quality control and signaling functions. ERES size, composition, architecture, interactions, and activity must be precisely remodeled in response to myriad pathophysiological cues to finely tune cellular homeostasis. However, the molecular mechanisms underlying this regulation remain incompletely understood. Coat protein complex II (COPII) mediates many ERES functions, and its subunits and client cargos are subject to spatiotemporal regulation by post-translational modifications (PTMs) that modulate ERES assembly, cargo selection, and inter-organelle communication. In this article, we review recent advances in understanding how PTMs control the organization and functional versatility of ERES and the COPII system.