Interaction of troponin components with F-actin and F-actin-tropomyosin complex.
1. Both TN-T and TN-I components of troponin interact with F-actin, causing its precipitation at 0.1 M KC1 and neutral pH in a form of highly ordered paracrystals, although the ability of TN-I component to precipitate of F-actin is much weaker. 2. F-actin paracrystals obtained in the presence of both TN-T and TN-I components consist of parallel arrays of F-actin filaments, although the fine structure is in each case different. 3. In the presence of tropomyosin in the proportion equal to that in muscle, less TN-T or TN-I component is needed to obtain full precipitation of F-actin. 4. Paracrystals of F-actin-tropomyosin-TN-T component and F-actin-tropomyosin-TN-I component show regular transverse striation spaced at about 380 A intervals. 5. The TN-C component of troponin solubilizes all precipitates of F-actin with TN-T or TN-I components, regardless of the presence of tropomyosin. 6. The results show that both TN-T or TN-I components can bind independently to F-actin-tropomyosin complex with the same periodicity, similar to that of the whole troponin in the living muscle.
D000199:Actins; D000818:Animals; D001665:Binding Sites; D003460:Crystallization; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D009124:Muscle Proteins; D009132:Muscles / Q000032:analysis; D011485:Protein Binding; D011817:Rabbits; D014335:Tropomyosin; D014336:Troponin
D000199:Actins; D046911:Macromolecular Substances; D009124:Muscle Proteins; D014335:Tropomyosin; D014336:Troponin