Muscle contraction sliding filament model

See also The Structure of Muscle, The Sliding Filament Model, The Role of Calcium in Contraction, Transverse Tubules... 

Figure 14.11 The sliding filament model of muscle contraction. The actin (red) and myosin (green) filaments slide past each other without shortening.

Studies on muscle contraction carried out between 1930 and 1960 heralded the modem era of research on cytoskeletal stmctures. Actin and myosin were identified as the major contractile proteins of muscle, and detailed electron microscopic studies on sarcomeres by H.E. Huxley and associates in the 1950s produced the concept of the sliding filament model, which remains the keystone to an understanding of the molecular mechanisms responsible for cytoskeletal motility. 

The sliding filament model describes the mechanism involved in muscle contraction. In this model, sarcomeres become shorter when the thin and thick filaments slide alongside each other and telescope together, with ATP being consumed. During contraction, the following reaction cycle is repeated several times ... 

Haselgrove, J. C., and Huxley, H. E. (1973). X-ray evidence for radial crossbridge movement and for the sliding filament model in actively contracting skeletal muscle. /. Mol. Biol. 77, 549-68. 

Figure 34.14. Sliding-Filament Model. Muscle contraction depends on the motion of thin fdaments (blue) relative to thick fdaments (red). [After H. E. Huxley. The mechanism of muscular contraction. Copyright 1965 hy Scientific American, Inc. All rights reserved.]... 

The sliding filament model explains the molecular basis by which muscular contraction occurs. During muscular contraction, thin filaments within the sarcomere of a myofibril are pulled towards the center of the sarcomere (called the H zone) by the thick filaments. In the process, the sarcomeric length shortens and the myofibril shortens. As a result, the muscle contracts (see Figure 8.11). Steps in the process include the following ... 

Muscle contraction can be explained by the sliding filament model on the basis of the structures illustrated in Figure 8.9a and described as follows ... 

Figure 8.10 The sliding filament model of muscle contraction. 

Describe muscle contraction in terms of the sliding-filament model, and relate contraction to changes in the sizes of the A band, I band, and H zone. 

Decide whether each of the following will remain unchanged or will decrease upon muscle contraction. Assume that the sliding-filament model applies. Refer to page 957 of the text. 

Structural Description of the Sliding Filament Model of Muscle Contraction... 

Figure 2.15. A primitive swinging cross-bridge/ sliding filament model of muscle contraction is introduced for the purpose of providing a conceptual bridge from the simple oil-like dissociation/assoda-tion for the opening/closing of a clam-shaped globular protein toward the more complex structural aspects of muscle contraction. Major limitations in...

Tirosh, R Liron, N. Oplatka, A. A hydrodynamic mechanism for muscular contraction. In Cross-Bridge Mechanism in Muscle Contraction, Proceedings of the International Symposium on the Current Problems of Sliding Filament Model and Muscle Mechanics, Tokyo, Japan, 1978. University of Tokyo Press Tokyo, 1979 pp. 593-609. 

Figure 14.12 The swinging cross-bridge model of muscle contraction driven by ATP hydrolysis, (a) A myosin cross-bridge (green) binds tightly in a 45 conformation to actin (red), (b) The myosin cross-bridge is released from the actin and undergoes a conformational change to a 90 conformation (c), which then rebinds to actin (d). The myosin cross-bridge then reverts back to its 45° conformation (a), causing the actin and myosin filaments to slide past each other. This whole cycle is then repeated.

The Sliding Filament Cross-Bridge Model Is the Foundation on Which Current Thinking About Muscle Contraction Is Built... 

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