This first figure is a good representation of how actin globulins combine to form the helical structure of the actin filament. Wrapped around it in light blue is the Tropomyosin structure, anchored down by the troponin complex (made of of Troponin T, C, and I). Troponin -T has an affinity towards tropomyosin, so it binds to it. Troponin-I has an affinity for actin so it is bound to the actin molecules. Troponin-c, has an affinity for Calcium. So once Ca+ enters the cell it binds to Troponin-C. The Troponin molecules interact with each other, therefore, when Ca+ binds to Troponin-C it has an effect on troponin-I and T causing tropomyosin to “slide out” out of the way- opening the binding sites for the Myosin x-Bridges to act on their affinity towards actin. Notice this figure also depicts the difference in Heavy and light chain myosin.
Here are some Pictures that may help with the visualization of some of the muscle structures and how they interact
February 9, 2011....
Cool Pics!
This cool figure shows the structure of the sarcomere, and includes Titin! Notice that the titin not only extends through the myosin, but also has an interaction with the actin near the z-disk. This picture is also great at depicting the different zones based on the interaction between actin and myosin (the light and dark bands as you would see in microscopy)
This should be a pretty useful picture when studying the steps of x-bridge cycling. This figure does a good job of showing the role of Atp and its importance in each part of the cycle. Note the binding of ATP is responsible for the RELEase of the myosin head, where as its Hydrolyzation and release of Pi is involved with the actual power stroke
Questions or comments? Butterfield.Lab@gmail.com
