| Project/Area Number |
10680628
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Biophysics
|
|---|
| Research Institution | Nagaoka University of Technology |
|---|
Principal Investigator |
HONDA Hajime Nagaoka University of Technology, Department of BioEngineering, Associate Professor, 工学部, 助教授 (20192742)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
MATSUNO Koichiro Nagaoka University of Technology, Department of BioEngineering, Professor, 工学部, 教授 (10120346)
IMAI Eiichi Nagaoka University of Technology, Department of BioEngineering, Research Assistant, 工学部, 教務職員 (30134977)
HATORI Kuniyuki Nagaoka University of Technology, Department of BioEngineering, Research Associate, 工学部, 助手 (00283036)
|
|---|
| Project Period (FY) |
1998 – 1999
|
| Project Status |
Completed (Fiscal Year 1999)
|
| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1998: ¥2,500,000 (Direct Cost: ¥2,500,000)
|
|---|
| Keywords | Actin / Myosin / Troponin / Tropomyosin / Sliding / Motility / ATPase / 分子集合体 / 運動性蛋白質 / 筋収縮 / アクチン繊維 / 分子間情報伝達 |
|---|
| Research Abstract |
1. An actin filament exhibits distortions longitudinally when it slides upon myosin molecules. We observed that the actin filament demonstrated contractile distortions for low ATP concentrations, while protractile ones for its high concentrations. Temporal development of such distortions was identified by tracing each of several speckled fluorescent markers attached to the actin filament. Close association of the sliding movement to the moving distortions of an actin filament suggests the presence of a unitary mechanism regulating the apparently two different modes of dynamic movement.
2. An actin filament contacting myosin molecules increased the fluctuation intensity of the filamental displacement as the ATP concentration increased. In particular, fluctuations in the filamental displacement in the planar plane in which the sliding movement takes place were isotropic at a low ATP concentration, and became anisotropic as the concentration increased. The buildup of the sliding movement of an actin filament was associated with the transformation from isotropic to anisotropic fluctuations of the filamental displacement.
3. Troponin extracted from rabbit skeletal muscle directly binds to an actin filament with the molar ratio of 1:3 in the absence of tropomyosin. An actin filament binding only to troponin did not exhibit any significant difference from an actin filament without troponin complex insofar as the maximum rate of act myosin ATP hydrolysis and the sliding velocity of the filament were focused in an in vitro motility assay, while the relative number of troponin-bound actin filaments moving in the absence of calcium ions was decreased down to 50% of that in the presence of calcium ions. The results indicate that troponin would transform an actin monomer within a filament into an OFF-state, implying that the onset of the sliding movement of the entire filament would require an appropriate arrangement of actin monomers in ON-state along the filament.
|
