Introduction to our Research

Signal transduction regulation by higher-order structural changes

The video above dynamically illustrates how a biological signal is relayed within the cell. First, a small molecule (ligand) mediating an extracellular signal binds to a protein on the cell surface. This binding triggers a subsequent chain of reactions involving association and dissociation of other proteins. In biological systems, signal transduction is usually mediated by physical contact between substances, with the major exception of neural signal transmission. Regulation of the affinity of the binding substances plays a key role in contact-mediated signal transduction.

In protein-mediated signal transduction, higher-order protein conformational changes control the binding affinity. As the animation illustrates, the binding of a protein with its ligand or another protein induces an alteration to its shape. Higher-order structural alterations associated with molecular binding, and subsequent changes in the binding affinities of downstream proteins, regulate biological signal transmission. We consider contact-mediated signaling pathways as a key arena for drug discovery. In essence, drugs are exogenous signal regulators. We carry out research to discover the biological nature of contact-mediated signal transduction mechanisms. For this purpose, we employ light-induced signaling models. Our topics include: light-induced protein structural changes and regulation of signal transduction by protein structural changes.