6klu | pdb_00006klu
Troponin of cardiac thin filament in high-calcium state
Structural highlights
Function[TNNC1_MOUSE] Troponin is the central regulatory protein of striated muscle contraction. Tn consists of three components: Tn-I which is the inhibitor of actomyosin ATPase, Tn-T which contains the binding site for tropomyosin and Tn-C. The binding of calcium to Tn-C abolishes the inhibitory action of Tn on actin filaments. [TNNI3_MOUSE] Troponin I is the inhibitory subunit of troponin, the thin filament regulatory complex which confers calcium-sensitivity to striated muscle actomyosin ATPase activity. [TNNT2_MOUSE] Troponin T is the tropomyosin-binding subunit of troponin, the thin filament regulatory complex which confers calcium-sensitivity to striated muscle actomyosin ATPase activity. Publication Abstract from PubMedTroponin 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 entire repeat of the thin filament. We determined the orientation of troponin relative to F-actin and tropomyosin, and characterized the interactions between troponin and tropomyosin. This study provides a structural basis for understanding the molecular mechanism of actomyosin system. Cryo-EM structures of cardiac thin filaments reveal the 3D architecture of troponin.,Oda T, Yanagisawa H, Wakabayashi T J Struct Biol. 2020 Jan 16:107450. doi: 10.1016/j.jsb.2020.107450. PMID:31954841[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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