The ins and outs of Ca2+ in plant endomembrane trafficking

- Calcium interacts with anionic phospholipids to regulate membrane trafficking.
- Endomembrane trafficking is regulated by Ca2+ sensing proteins.
- Endomembrane trafficking overlap with membrane integrity maintenance mechanisms.
- Graded Ca2+ distribution along the endomembrane system steers protein sorting.

Trafficking of proteins and lipids within the plant endomembrane system is essential to support cellular functions and is subject to rigorous regulation. Despite this seemingly strict regulation, endomembrane trafficking needs to be dynamically adjusted to ever-changing internal and environmental stimuli, while maintaining cellular integrity. Although often overlooked, the versatile second messenger Ca2+ is intimately connected to several endomembrane-associated processes. Here, we discuss the impact of electrostatic interactions between Ca2+ and anionic phospholipids on endomembrane trafficking, and illustrate the direct role of Ca2+ sensing proteins in regulating endomembrane trafficking and membrane integrity preservation. Moreover, we discuss how Ca2+ can control protein sorting within the plant endomembrane system. We thus highlight Ca2+ signaling as a versatile mechanism by which numerous signals are integrated into plant endomembrane trafficking dynamics.