CHAPTER 5: Small Molecule Inhibitors of E3 Ubiquitin Ligases

Protein–protein interaction is one of the important events in signal transduction pathways and this interaction is frequently induced by protein phosphorylation. For this interaction, several domains in proteins are known to specifically recognize the phosphorylated residues of target proteins. Previously, we have reviewed small molecule inhibitors for phosphorylation-dependent protein–protein interaction, especially for 14-3-3 or polo box domain (PBD)-dependent binding. F-box proteins, the substrate recognition subunit in SCF ubiquitin ligases, are one of the common examples of such phosphorylation-dependent interaction. In this chapter, we have focused on the several small molecule inhibitors of F-box proteins, especially S-phase kinase-associated protein 2 (Skp2). Skp2-dependent interaction is known to be important in the progression of diseases caused by disordered signal transduction, such as cancer. Thus, small molecules that modulate this interaction are attractive lead compounds for the treatment of such diseases. In addition, we have summarized some small molecule inhibitors of other F-box proteins.