Opening up Vps34 protein complexes During intracellular membrane trafficking, large protein complexes regulate and adapt the activity of signal transducer enzymes such as the class III phosphatidylinositol 3-kinase Vps34. These large enzyme complexes are present in all eukaryotic cells, having widespread importance in neurodegeneration, aging, and cancer; however, a structural understanding has been lacking. Rostislavleva et al. provide atomic-resolution insights into the structures of the Vps34-containing protein complexes required for autophagy, endocytic sorting, and cytokinesis. The V-shaped complexes can undergo opening motions, which allows them to adapt to and phosphorylate membranes. Science , this issue p. 10.1126/science.aac7365