5MVA

Structure of the thin filament at high calcium concentration

5MVA の概要

• エントリーDOI: 10.2210/pdb5mva/pdb
• EMDBエントリー: 3576
• 分子名称: Actin, alpha skeletal muscle, ADENOSINE-5'-DIPHOSPHATE (2 entities in total)
• 機能のキーワード: thin filament, troponin, actin, tropomyosin, structural protein
• 由来する生物種: Oryctolagus cuniculus (Rabbit)
• 細胞内の位置: Cytoplasm, cytoskeleton: P68135
• タンパク質・核酸の鎖数: 23
• 化学式量合計: 972965.18

構造登録者

Paul, D.M.,Squire, J.M.,Morris, E.P. (登録日: 2017-01-16, 公開日: 2017-11-29, 最終更新日: 2025-04-09)

主引用文献

Paul, D.M.,Squire, J.M.,Morris, E.P.
Relaxed and active thin filament structures; a new structural basis for the regulatory mechanism.
J. Struct. Biol., 197:365-371, 2017

PubMed Abstract: The structures of muscle thin filaments reconstituted using skeletal actin and cardiac troponin and tropomyosin have been determined with and without bound Ca using electron microscopy and reference-free single particle analysis. The resulting density maps have been fitted with atomic models of actin, tropomyosin and troponin showing that: (i) the polarity of the troponin complex is consistent with our 2009 findings, with large shape changes in troponin between the two states; (ii) without Ca the tropomyosin pseudo-repeats all lie at almost equivalent positions in the 'blocked' position on actin (over subdomains 1 and 2); (iii) in the active state the tropomyosin pseudo-repeats are all displaced towards subdomains 3 and 4 of actin, but the extent of displacement varies within the regulatory unit depending upon the axial location of the pseudo-repeats with respect to troponin. Individual pseudo-repeats with Ca bound to troponin can be assigned either to the 'closed' state, a partly activated conformation, or the 'M-state', a fully activated conformation which has previously been thought to occur only when myosin heads bind. These results lead to a modified view of the steric blocking model of thin filament regulation in which cooperative activation is governed by troponin-mediated local interactions of the pseudo-repeats of tropomyosin with actin.

PubMed: 28161413
DOI: 10.1016/j.jsb.2017.01.004

実験手法

ELECTRON MICROSCOPY (27.7 Å)