Cover Photograph: Through the looking glass: The role of metabolites. Cells contain a vast amount of small metabolites that may interact with proteins and thus regulate protein localization and turnover, protein-protein interactions and binding of proteins to nucleic acids among other things. In this issue (pages 485–489), Li and Snyder take a look at the different strategies used to discover metaboliteprotein interactions and identify several challenges faced by these approaches. A systematic investigation of metaboliteprotein interactions may help bridge the gap between genome-wide association studies and small molecule screening studies and therefore lead to disclosure of important aspects of physiology and pathology. These findings may ultimately even provide a short list of potential targets and small molecule candidates for drug development.

Cover by X. Li and M. Snyder