Cell shape is adapted to function. Organelle shape is likewise optimised for the processes that take place on and within these microenvironments. Our research focuses on the dynamic regulation of cell and organelle shape and the ways in which transport containers bud from membranes and fuse with other membranes. An understanding of these processes is necessary to fully appreciate synapse function, the mechanisms of cell surface receptor expression, signalling within the cell and the uptake of nutrients. Furthermore, these pathways may be hijacked by viruses and toxins to gain entry into cells and may be dysregulated in pathological conditions such as cancer. We have found that the dynamic regulation of membrane curvature can occur through the interplay between the regulated insertion of membrane bending proteins (e.g. ENTH domains/amphipathic helices) and the sensing of membrane curvature by BAR domain-containing proteins. To further understand this process we solved the structures of a number of BAR domains, and have defined the molecular pathways on which they function. We have also defined the molecular mechanisms by which ENTH domains and amphipathic helices bend membranes. The use of such tools by the cell is not limited to the uptake of nutrients and signalling from the surrounding environment (endocytosis) but is also essential for most trafficking pathways within cells. We have tried to move in 2 directions with our new understanding. In the first instance we apply our knowledge to understand the complexity of neuronal connections and the ability of neurons to fire in a fast and reliable manner. In the second instance we have moved to a deeper understanding of transport container formation with controlled in vitro reconstitution of membrane budding stages (for example, some of the stages of clathrin-mediated endocytosis). We believe that we will eventually be able to manipulate and investigate at will, the control points and detailed mechanisms of endocytosis. The current view of clathrin-mediated endocytosis is simplistic, since there are probably many different pathways involving clathrin and many distinct adaptor proteins, so that cells can tightly control which ligands are taken up at any point in time and space thereby regulating surface receptor expression. The complete reconstitution of clathrin-mediated endocytosis will also allow us to test different models and to examine the role of each individual protein.