They grow up so fast - the birth and development of membrane contact site research

Over the past 15 years, the field of 'membrane contact sites' and research into direct communication between organelles has taken off. In this Perspective, we look back at how the field has developed. Rather than cover every forward step, we focus on conceptual advances in the study of interorganelle communication - particularly advances that were not obvious at the start of this journey. Among these advances is the demonstration that different functions located at the same membrane contact site interact with each other. Another is that a wide range of molecules are transferred between organelles at contact sites, well beyond the two best-known cargos, Ca2+ and lipids. By looking at the history of the field, we explain how our understanding of Ca2+ flux and lipid transfer have grown at different rates. Finally, we suggest that the field has been liable to several types of error, from concrete thinking about the significance of contact to misusing terms such as 'tether'. Nevertheless, the application of new cutting-edge techniques to the future of contact site research presents many exciting opportunities.