Future Frontiers in Small Molecule Inhibitors of Protein-Protein Interactions

Protein-protein interactions (PPIs) are ubiquitous in essential biological processes such as cell proliferation and differentiation, host-pathogen interactions, and signal transduction pathways [1]. Pioneering advances in the field of interactomics have uncovered new net-works of protein interactions within cells, with esti-mates for the size of the interactome ranging up to 650,000 PPIs [2]. However, targeting PPIs has histori-cally been considered to be a particularly challenging task due to their typically large size (>1,500 Å) and amorphous nature that lack well-defined crevices for recognition by small molecules. Not surprisingly, the pharmaceutical landscape over the last century has been dominated by programs for small molecule in-hibitors of enzymes (particularly kinases), G-protein-coupled receptors, protein transporters and ion chan-nels that account for the majority of known drugs