Proposed model for Arf1-PI4KIIIβ positive vesicles function at lysosomal tubules fission site. (1) Formation of lysosomal tubules from lysosomes, autolysosomes, endolysosomes, and phagolysosomes requires PI(4)P on the cytosolic leaflet of the lysosome membrane. (2 i and ii) Arf1-PI4KIIIβ positive vesicles are recruited to lysosomal tubule fission events, where the ER is also present. At these tri-organelle contact sites, we propose that SEC14L2 on the Arf1-PI4KIIIβ positive vesicle mediates a PI(3)P signal on the lysosomal membrane by (i) transferring PI(3)P from the vesicle to the lysosome, or (ii) regulating the activity of PI(3)P production machinery on lysosomes. These two mechanisms are not mutually exclusive. (3) PI(3)P signaling on tubules leads to fission of the tubule allowing for lysosome reformation from parent lysosome organelles (autolysosomes, endolysosomes, or phagolysosomes) or membrane trafficking events. Lysosomes are depicted in magenta, Arf1-PI4KIIIβ positive vesicles in green and the ER in gray.