Myosin translation

Chantler, P., and Bower, S.M. (1988) Cross-linking between translationally equivalent sites on the heads of myosin Relationship to energy transfer results between the same pair of sites./. Biol. Chem. 263, 938. 

Valouev lA, Urakov VN, Kochneva-Pervukhova NV, Smirnov VN, Ter-Avanesyan MD (2004) Translation termination factors function outside of translation yeast eRFl interacts with myosin light chain, Mlclp, to effect cytokinesis. Mol Microbiol 53 687-696... 

A typical low-angle diffraction pattern from relaxed bony fish muscle is shown in Fig. 4B. Much of the intensity that is seen comes from the organization of the myosin heads on the myosin filaments in the resting state (probably mainly MADP.Pi). We know that the myosin heads lie approximately on three co-axial helices of subunit translation 143 A and repeat 429 A. This is most easily represented by the radial net shown in Fig. 16B-D. The radial net in D is like an opened-out surface view of the filament in B. Here the helical tracks become straight lines, and the black blobs represent the origins on the myosin filament surface of the pairs of myosin heads in each myosin molecule. From early studies it is known that the three crowns within the 429 A repeat are not exactly the same and that there is a perturbation. 

Figure 6.3. Stractuie and function of myofilaments, a Arrangement of proteins within the filaments, b, c Mechanism of myofilament motion. Calcium binds to troponin, which in tnm causes tropomyosin to move and expose the myosin binding site on actin. Binding to actin canses the myosin heads to kink, which translates into a sliding motion, c The kinked conformation of myosin cleaves ATP. In the process, myosin releases itself from actin and letnms to the extended conformation it then binds to another actin monomer, and the cycle is repeated.

The horse, like all animals, is powered by the molecular motor protein, myosin. A portion of myosin moves dramatically (as shown above) in response to ATP binding, hydrolysis, and release, propelling myosin along an actin filament. This molecular movement is translated into movement of the entire animal, excitingly depicted in da Vinci s rearing horse. [(Left) Leonardo da Vinci s "Study of a rearing horse" for the battle of Anghiari (c. 1504) from The Royal Collection Her Royal Majesty Queen Elizabeth II.]... 

On the other hand, it has been suggested, based on immunopre-cipitation reactions, that CCT might interact with a broad range (accounting for 9-15%) of newly synthesized eukaryotic proteins (Feldman and Frydman, 2000 McCallum et al., 2000 Thulasiraman et al., 1999). There is also evidence that some proteins other than actins and tubulins fold via interaction with CCT. These include G -transducin (Farr etal, 1997), cyclinE (Won etal., 1998), and the von Hippel-Landau tumor suppressor protein VHL (Feldman et al., 1999). Moreover, translation in vitro of myosin heavy and light chains has identified an intermediate in the biogenesis of the heavy meromyosin subunit (HMM) of skeletal muscle myosin that contains all three myosin subunits and CCT, from which partially folded HMM can be released in an ATP-dependent reaction. Other as yet unknown cytosolic protein(s) are also apparently required for the completion of the myosin folding reaction (Srikakulam and Winkelmann, 1999). 

Proteins are ubiquitous. Not only are gene transcription and translation carried out by proteins, but other proteins are involved notably in muscle contraction examples are myosin and actin. Still others, for example, are those called the histone proteins, repressor proteins, and proteins in the ribosomes. 

One way to place an apparent load into the system is to mix a myosin that has a high rate of actin filament translation with a myosin that moves actin more slowly (Sellers etaZ., 1985 Warshaw eZflZ., 1990 Harris etaZ.,... 

The basic mechanism for force generation is accepted to be the same in all three vertebrate muscle types the cyclic interaction between actin and myosin (Taylor, 1987). The binding of ATP to actomyosin (AM), hydrolysis of ATP, and eventual release from AM of ADP and Pj results in a large change in free energy that is translated into a force-producing conformation change and translocation of thin and thick filaments relative to one another. 

Helical symmetry The polymeric proteins of filamentous viruses and the cytoskel-ton possess helical symmetry, in which subunits are related by a translation, as well as a rotational component. Actin, myosin, tubulin and various other fibrous proteins all interact with helical symmetry, which is often called screw symmetry. Screw symmetry, which relates the positions of adjacent subunits, combines a translation along the helix axis with the rotation. Actin forms a two-stranded helix of globular actin subunits. However, important variations in the helix parameters occur (Egehnan et al, 1982). The rise per subunit is relatively constant, but the twist or relative rotation around the helix axis is highly variable. This polymorphic tendency is probably important for the smooth functioning of muscle contraction, which involves considerable force generation. 

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