Mediates the transfer of lipids between membranes at organelle contact sites (PubMed:30093493, PubMed:24036347, PubMed:22442115). Binds phospholipids, including phosphatidic acid (PA), phosphorylated phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylethanolamine (PE), ceramide, and phosphatidylserine (PS) (PubMed:30093493, PubMed:34830155, PubMed:28122955, PubMed:28334785). Involved in mitochondrial lipid homeostasis, in a MCP1-dependent manner (PubMed:27280386, PubMed:34830155, PubMed:32690699). Involved in cortical reticulophagy (also known as cortical endoplasmic reticulum (ER) macroautophagy), acting at the late endosome to package ER into autophagosomes (PubMed:32690699). Involved in the formation of the prospore membrane during sporulation, in a SPO71-dependent manner (PubMed:24036347, PubMed:22442115). Involved in Golgi vesicle transport, in a CDC31-dependent and ARF1-dependent manner (PubMed:28122955, PubMed:9314526, PubMed:34830155). Plays a role in actin cytoskeleton organization (PubMed:28334785). Interacts (via SHR-BD domain) with SPO71 (via PxP motif); during prospore membrane formation (PubMed:24036347, PubMed:30018089). Interacts (via SHR-BD domain) with YPT35 (via PxP motif) (PubMed:30018089). Interacts (via SHR-BD domain) with MCP1 (via PxP motif) (PubMed:30018089, PubMed:28864540). Interacts with CDC31 (PubMed:28122955). Interacts (via C-terminus) with ARF1; the interaction is direct (PubMed:34830155). Interacts with the actin cytoskeleton (PubMed:28334785). Found at different interorganellar contact sites depending on the growth state of the cell (PubMed:26370498, PubMed:27280386, PubMed:30018089, PubMed:32690699). Localizes from endosomes to the vacuolar membrane during starvation (PubMed:32690699). Localizes to mitochondrial-endosome contacts (PubMed:27280386). Localizes to nuclear envelope-vacuole contact sites (nuclear-vacuole junction; NVJ) during respiration (PubMed:26370498, PubMed:27280386, PubMed:30018089). The SHR-BD domain binds to PxP motifs found in interaction partners. Compromises mitochondrial function and integrity, increases mitophagy (PubMed:27280386, PubMed:34830155, PubMed:32690699). Vacuolar protein missorting (PubMed:27280386, PubMed:28334785). Decreases number of clathrin-coated vesicles in cell (PubMed:34830155). Abnormal cortical reticulophagy; decreases packaging of endoplasmic reticulum (ER) into autophagosomes (PubMed:32690699). Abnormal sporulation; defective prospore membrane formation (PubMed:27280386, PubMed:24036347, PubMed:22442115). Accumulation of vesicles within the prospore membrane lumen and reduction of phosphatidylinositol and phosphatidic acid in the membrane (PubMed:22442115, PubMed:24036347). Abnormal actin cytoskeleton organization (PubMed:28334785). Sensitive to the arginine analog canavanine (PubMed:34830155, PubMed:28334785). Synthetic lethal with MMM1 (PubMed:26370498, PubMed:27280386). Localization of SPO71 to the prospore membrane is normal (PubMed:24036347). Present with 125 molecules/cell in log phase SD medium. Belongs to the VPS13 family.