The Intriguing Dual Lattices of the Myosin Filaments in Vertebrate Striated Muscles: Evolution and Advantage
1
Molecular Medicine Section, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
2
Muscle Contraction Group, School of Physiology & Pharmacology, University of Bristol, Bristol BS8 1TD, UK
3
Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
*
Author to whom correspondence should be addressed.
Biology 2014, 3(4), 846-865; https://doi.org/10.3390/biology3040846
Received: 5 September 2014 / Revised: 20 November 2014 / Accepted: 25 November 2014 / Published: 3 December 2014
(This article belongs to the Special Issue Muscle Structure and Function)
Myosin filaments in vertebrate striated muscle have a long roughly cylindrical backbone with cross-bridge projections on the surfaces of both halves except for a short central bare zone. In the middle of this central region the filaments are cross-linked by the M-band which holds them in a well-defined hexagonal lattice in the muscle A-band. During muscular contraction the M-band-defined rotation of the myosin filaments around their long axes influences the interactions that the cross-bridges can make with the neighbouring actin filaments. We can visualise this filament rotation by electron microscopy of thin cross-sections in the bare-region immediately adjacent to the M-band where the filament profiles are distinctly triangular. In the muscles of teleost fishes, the thick filament triangular profiles have a single orientation giving what we call the simple lattice. In other vertebrates, for example all the tetrapods, the thick filaments have one of two orientations where the triangles point in opposite directions (they are rotated by 60° or 180°) according to set rules. Such a distribution cannot be developed in an ordered fashion across a large 2D lattice, but there are small domains of superlattice such that the next-nearest neighbouring thick filaments often have the same orientation. We believe that this difference in the lattice forms can lead to different contractile behaviours. Here we provide a historical review, and when appropriate cite recent work related to the emergence of the simple and superlattice forms by examining the muscles of several species ranging back to primitive vertebrates and we discuss the functional differences that the two lattice forms may have.
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Keywords:
vertebrate striated muscle; electron microscopy; X-ray diffraction; myosin filament lattice; thick filament; myosin filament; M-band; bare-region
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MDPI and ACS Style
Luther, P.K.; Squire, J.M. The Intriguing Dual Lattices of the Myosin Filaments in Vertebrate Striated Muscles: Evolution and Advantage. Biology 2014, 3, 846-865. https://doi.org/10.3390/biology3040846
AMA Style
Luther PK, Squire JM. The Intriguing Dual Lattices of the Myosin Filaments in Vertebrate Striated Muscles: Evolution and Advantage. Biology. 2014; 3(4):846-865. https://doi.org/10.3390/biology3040846
Chicago/Turabian StyleLuther, Pradeep K.; Squire, John M. 2014. "The Intriguing Dual Lattices of the Myosin Filaments in Vertebrate Striated Muscles: Evolution and Advantage" Biology 3, no. 4: 846-865. https://doi.org/10.3390/biology3040846
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