Thousands of chemical reactions take place in cells every second, and many of them must take place at the correct location on a specific intracellular membrane. An enzyme called VPS34, also known as class III PI3K, has a crucial role in this process, as does a family of proteins known as Rab GTPases. VPS34 is conserved in all eukaryotes, regulating core “housekeeping” signalling pathways, such as autophagy and endosomal trafficking.