Summary: Vesicle-associated membrane protein (VAMP)-associated proteins (VAPs) are highly conserved endoplasmic reticulum (ER)-resident proteins that establish ER contacts with multiple membrane compartments in many eukaryotes.However, VAP-mediated membrane-tethering mechanisms remain ambiguous.Here, focusing on fission yeast ER-plasma membrane (PM) contact formation, using systematic interactome analyses and quantitative microscopy, we predict a non-VAP-protein direct binding-based ER-PM coupling.We further reveal that VAP-anionic phospholipid interactions may underlie ER-PM association and define Butter Dish Lid the pH-responsive nature of VAP-tethered membrane contacts.
Such conserved interactions with anionic phospholipids are generally defective in amyotrophic lateral sclerosis-associated human VAPB mutant.Moreover, we identify a conserved FFAT-like motif locating at the autoinhibitory hotspot of Train Sets the essential PM proton pump Pma1.This modulatory VAP-Pma1 interaction appears crucial for pH homeostasis.We thus propose an ingenious strategy for maintaining intracellular pH by coupling Pma1 modulation with pH-sensory ER-PM contacts via VAP-mediated interactions.