Efficient copying of nonhomologous sequences from ectopic sites via P-element-induced gap repair.

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Abstract
Troponin is an essential component of striated muscle and it regulates the sliding of actomyosin system in a calcium-dependent manner. Despite its importance, the structure of troponin has been elusive due to its high structural heterogeneity. In this study, we analyzed the 3D structures of murine cardiac thin filaments using a cryo-electron microscope equipped with a Volta phase plate (VPP). Contrast enhancement by a VPP enabled us to reconstruct the 3D structure of the thin filament in low-calcium and high-calcium states. We revealed the conformational changes in troponin that translocate tropomyosin as well as the detailed 3D architecture of the whole troponin-tropomyosin complex. However, we faced fierce objections from the scientific community that it is meaningless to interpret our data because we fixed the specimen using glutaraldehyde to stabilize troponin attachment to the thin filament. Nonetheless, we believe that glutaraldehyde fixation did not significantly affect our conclusions. Therefore, we decided to share our data via the preprint server instead of peer-reviewed journals.