Biomaterial Database

"Crystalline" myosin cross-bridge array in relaxed bony fish muscle. Low-angle x-ray diffraction from plaice fin muscle and its interpretation. 1986

J Harford, and J Squire

Detailed structural analysis of muscles normally used to study myosin cross-bridge behavior (e.g., frog sartorius muscle, insect flight muscle) is extremely difficult due to the statistical disorder inherent in their myosin filament arrays. Bony fish muscle is different from all other muscle types in having a myosin filament (A-Band) array with good three-dimensional (crystalline) regularity that is coherent right across each myofibril. Rigorous structure analysis is feasible with fish muscle. We show that low-angle x-ray diffraction patterns from plaice fin muscle contain characteristic vertebrate layer lines at orders of 429 (+/- 0.2) A, that these layer lines are well sampled by row-lines from a simple hexagonal lattice of a-spacing 470 (+/- 2.0) A at rest length and that there are meridional reflections, due to axial perturbations of the basic helix of myosin heads, similar in position to those from frog muscle but differing in relative intensities. Clear trends based on modeling to a resolution of 130 A of the observed intensities in the low angle x-ray diffraction pattern from relaxed plaice fin muscle suggest that: (a) the pattern out to 130 A is more sensitive to the distribution of the two heads than it is to details of the head shape, (b) both heads in one myosin molecule probably tilt axially in the same direction by approximately 20-40 degrees relative to a normal to the thick filament backbone, (c) the center of mass of the heads is at 145 to 160 A radius, and (d) the two heads form a compact structure by lying closely adjacent to each other and almost parallel. Little rotational disorder of the heads can occur. Because of its crystallinity, bony fish muscle provides a uniquely useful structural probe of myosin cross-bridge behavior in other muscle states such as rigor and active contraction.

UI	MeSH Term	Description	Entries
D008958	Models, Molecular	Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.	Molecular Models,Model, Molecular,Molecular Model
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009126	Muscle Relaxation	That phase of a muscle twitch during which a muscle returns to a resting position.	Muscle Relaxations,Relaxation, Muscle,Relaxations, Muscle
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D009218	Myosins	A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain.	Myosin ATPase,ATPase, Actin-Activated,ATPase, Actomyosin,ATPase, Myosin,Actin-Activated ATPase,Actomyosin ATPase,Actomyosin Adenosinetriphosphatase,Adenosine Triphosphatase, Myosin,Adenosinetriphosphatase, Actomyosin,Adenosinetriphosphatase, Myosin,Myosin,Myosin Adenosinetriphosphatase,ATPase, Actin Activated,Actin Activated ATPase,Myosin Adenosine Triphosphatase
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D005399	Fishes	A group of cold-blooded, aquatic vertebrates having gills, fins, a cartilaginous or bony endoskeleton, and elongated bodies covered with scales.
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D014961	X-Ray Diffraction	The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Xray Diffraction,Diffraction, X-Ray,Diffraction, Xray,Diffractions, X-Ray,Diffractions, Xray,X Ray Diffraction,X-Ray Diffractions,Xray Diffractions
D046911	Macromolecular Substances	Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.	Macromolecular Complexes,Macromolecular Compounds,Macromolecular Compounds and Complexes,Complexes, Macromolecular,Compounds, Macromolecular,Substances, Macromolecular