6KN7

Structure of human cardiac thin filament in the calcium free state

Summary for 6KN7

• Entry DOI: 10.2210/pdb6kn7/pdb
• EMDB information: 0728
• Descriptor: Actin, alpha skeletal muscle, Tropomyosin alpha-1 chain, Troponin T, cardiac muscle, ... (7 entities in total)
• Functional Keywords: troponin, tropomyosin, actin, thin filement, muscle, contractile protein-actin binding protein complex, contractile protein/actin binding protein
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 29
• Total formula weight: 896581.87

Authors

Fujii, T.,Yamada, Y.,Namba, K. (deposition date: 2019-08-03, release date: 2020-01-15, Last modification date: 2024-03-27)

Primary citation

Yamada, Y.,Namba, K.,Fujii, T.
Cardiac muscle thin filament structures reveal calcium regulatory mechanism.
Nat Commun, 11:153-153, 2020

PubMed Abstract: Contraction of striated muscles is driven by cyclic interactions of myosin head projecting from the thick filament with actin filament and is regulated by Ca released from sarcoplasmic reticulum. Muscle thin filament consists of actin, tropomyosin and troponin, and Ca binding to troponin triggers conformational changes of troponin and tropomyosin to allow actin-myosin interactions. However, the structural changes involved in this regulatory mechanism remain unknown. Here we report the structures of human cardiac muscle thin filament in the absence and presence of Ca by electron cryomicroscopy. Molecular models in the two states built based on available crystal structures reveal the structures of a C-terminal region of troponin I and an N-terminal region of troponin T in complex with the head-to-tail junction of tropomyosin together with the troponin core on actin filament. Structural changes of the thin filament upon Ca binding now reveal the mechanism of Ca regulation of muscle contraction.

PubMed: 31919429
DOI: 10.1038/s41467-019-14008-1

Experimental method

ELECTRON MICROSCOPY (6.6 Å)