Possible formation of a triple-stranded coiled-coil region in tropomyosin-troponin T binding complex

Immunoelectron microscopy has shown that the spatial arrangement of troponin T on tropomyosin can be represented as a structure of approximately 90 Å in length, as shown in Figure 1. The region of residues 90 to 148 of troponin T, which has been confirmed as a main part of the fragment which specifically binds to tropomyosin, was predicted to be a long stretch of α-helix by the method of secondary structure prediction. Furthermore, the mechanism of the specific binding was explored on the basis of the coiled-coil structure of tropomyosin by a simple scoring method. One of the most feasible structures of the specific binding complex was a triple-stranded coiled-coil made between a tropomyosin coiled-coil and the α-helical region of the specific binding fragment of troponin T. It is illustrated as a stereo view in Figure 2.