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Structure of the Actin-Tropomyosin-Myosin Complex (rigor ATM 3)Structure of the Actin-Tropomyosin-Myosin Complex (rigor ATM 3)
Structural highlights
Function[ACTS_RABIT] Actins are highly conserved proteins that are involved in various types of cell motility and are ubiquitously expressed in all eukaryotic cells. [MYOE_DICDI] Myosin is a protein that binds to actin and has ATPase activity that is activated by actin. May play a role in moving membranes relative to actin. [TPM1_RABIT] Binds to actin filaments in muscle and non-muscle cells. Plays a central role, in association with the troponin complex, in the calcium dependent regulation of vertebrate striated muscle contraction. Smooth muscle contraction is regulated by interaction with caldesmon. In non-muscle cells is implicated in stabilizing cytoskeleton actin filaments. Publication Abstract from PubMedRegulation of myosin and filamentous actin interaction by tropomyosin is a central feature of contractile events in muscle and nonmuscle cells. However, little is known about molecular interactions within the complex and the trajectory of tropomyosin movement between its "open" and "closed" positions on the actin filament. Here, we report the 8 A resolution structure of the rigor (nucleotide-free) actin-tropomyosin-myosin complex determined by cryo-electron microscopy. The pseudoatomic model of the complex, obtained from fitting crystal structures into the map, defines the large interface involving two adjacent actin monomers and one tropomyosin pseudorepeat per myosin contact. Severe forms of hereditary myopathies are linked to mutations that critically perturb this interface. Myosin binding results in a 23 A shift of tropomyosin along actin. Complex domain motions occur in myosin, but not in actin. Based on our results, we propose a structural model for the tropomyosin-dependent modulation of myosin binding to actin. Structure of the rigor actin-tropomyosin-Myosin complex.,Behrmann E, Muller M, Penczek PA, Mannherz HG, Manstein DJ, Raunser S Cell. 2012 Jul 20;150(2):327-38. PMID:22817895[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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