Transient Ca2+ fluctuations on the surface of the endoplasmic reticulum (ER) can induce liquid-liquid phase separation (LLPS) of the autophagy initiation complex FIP200, forming FIP200 puncta and triggering autophagosome formation. However, the mechanisms by which these transient Ca2+ fluctuations persist during autophagy induction, and how they are decoded to trigger the formation of FIP200 puncta, remain unclear.
