Bar domain genetic screen and phenotypes. (A) Drosophila BAR domain gene expression scores (modENCODE, FlyBase; Graveley et al., 2011; Gramates et al., 2022) in SGs before (black bars) and after the secretion phase (gray bars). The 11 genes expressed above threshold (red line), were included in our screen. (B) Time-lapse sequence of representative LSVs from BAR domain KD SGs (SRRF intensity-projection) undergoing kiss-and-run (KAR; CIP4^KD; top two rows; “deforming” LSV—dashed line; consecutive fusion events at 00:00 and 03:12—asterisk), full collapse (FC; SNX1^KD and MIM^KD; third and fourth rows; expanding fusion pore—double arrowheads; fusion—asterisk) and compound exocytosis (SNX6^KD; bottom; fusion—asterisks). In compound exocytosis, we see that after fusion, LSVs fuse consecutively to an LSV fused to the cell membrane, creating a large “blob.” Glue-GFP (green) and LifeAct-Ruby (magenta). RNAi expressed under UAS control. UAS expression driven by fkh-Gal4. Time mm:ss; relative to fusion. Scale bars in KAR and FC 1 µm, in Compound exocytosis 10 µm.