|Budget Amount *help
¥585,000,000 (Direct Cost: ¥450,000,000、Indirect Cost: ¥135,000,000)
Fiscal Year 2006: ¥119,600,000 (Direct Cost: ¥92,000,000、Indirect Cost: ¥27,600,000)
Fiscal Year 2005: ¥118,300,000 (Direct Cost: ¥91,000,000、Indirect Cost: ¥27,300,000)
Fiscal Year 2004: ¥119,600,000 (Direct Cost: ¥92,000,000、Indirect Cost: ¥27,600,000)
Fiscal Year 2003: ¥110,500,000 (Direct Cost: ¥85,000,000、Indirect Cost: ¥25,500,000)
Fiscal Year 2002: ¥117,000,000 (Direct Cost: ¥90,000,000、Indirect Cost: ¥27,000,000)
Biological functions are inherently hierarchical. We planned to investigate the underlying mechanism of biological functions from the single-molecular level to the level of supramolecular assemblies, focusing on the mechanism characteristic of each level of hierarchy. Our study was focused primarily on a biological motility system starting from interactions between single-molecular motors and track polymers, to whole ensembles of such interactions (nanomuscle, myofibrils and fibers), and on to single cells and whole tissues (the heart). We also aimed to develop a technique that will allow the use of the cytoskeleton as a "bionanogauge". The main results of this project are summarized as follows: 1) Microscopic measurements of unbinding force of actin-myosin V or VI complex under various concentrations of ADP showed that the apparent binding affinity of ADP depends on the loading direction. Based on a simple model analysis, we could determine the load dependence of the attachment and detachment rate constants of ADP to actomyosin complex, which helped understanding of the molecular mechanism of myosin motility. 2) We have demonstrated that the fluorescence intensity of rhodamine-labeled single actin filaments changes depending on the applied load, implying that the local structure of actin is distorted. 3) We presented evidence for that the changes of filament lattice are responsible for the mechanism of SPOC of myofibrils. 4) We have succeeded in identifying the amino acids of tubulin that are responsible for the strong binding of kinesin using genetically engineered tubulin molecules. 5) Using a micro-thermometer, we could find that the application of ionomycin induced the temperature increase by 1℃ in single HeLa cells, which is attributable to the Ca^<2+> uptake. 6) Using the Photon Counting Histogram technique, we showed that actin filaments consist of not only helical polymers but also linear polymers as theoretically predicted by F. Oosawa and his associates.