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Structure, function and evolution of insect flight muscle

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ABSTRACT

Insects, the largest group of animals on the earth, owe their prosperity to their ability of flight and small body sizes. The ability of flight provided means for rapid translocation. The small body size allowed access to unutilized niches. By acquiring both features, however, insects faced a new problem: They were forced to beat their wings at enormous frequencies. Insects have overcome this problem by inventing asynchronous flight muscle, a highly specialized form of striated muscle capable of oscillating at >1,000 Hz. This article reviews the structure, mechanism, and molecular evolution of this unique invention of nature.

No MeSH data available.


Related in: MedlinePlus

Match-mismatch theory of stretch activation. The diagram shows the relations among 6 thin filaments (pink lines) surrounding a thick filament, the positions of target zones on the thin filament (red circles) and the positions of myosin heads (dots). Myosin heads bound to actin are represented as green circles. In (a) most of myosin heads are unable to bind to actin, but after a ~20-nm stretch, many myosin heads can bind to actin.
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f6-7_21: Match-mismatch theory of stretch activation. The diagram shows the relations among 6 thin filaments (pink lines) surrounding a thick filament, the positions of target zones on the thin filament (red circles) and the positions of myosin heads (dots). Myosin heads bound to actin are represented as green circles. In (a) most of myosin heads are unable to bind to actin, but after a ~20-nm stretch, many myosin heads can bind to actin.

Mentions: The ability of SA, as mentioned above, is considered essential for the asynchronous operation of IFM, and many investigators have pursued its molecular mechanism. The characteristically high regularity of protein arrangement led to the proposal of the “match-mismatch hypothesis10”, which assumes that a stretch brings actin and myosin into right geometry for interaction. In general, only a limited number of actin monomers on a thin filament are suitably oriented for interaction with myosin heads. These monomers are clustered in small areas called “target zones”. The target zones on the 6 thin filaments surrounding a thick filament are helically arranged (Fig. 6). At a certain sarcomere length, none of the myosin heads are close to the target zones. However, a 19-nm stretch of the sarcomere will bring the myosin heads close enough to interact with actins in the target zones, causing SA.


Structure, function and evolution of insect flight muscle
Match-mismatch theory of stretch activation. The diagram shows the relations among 6 thin filaments (pink lines) surrounding a thick filament, the positions of target zones on the thin filament (red circles) and the positions of myosin heads (dots). Myosin heads bound to actin are represented as green circles. In (a) most of myosin heads are unable to bind to actin, but after a ~20-nm stretch, many myosin heads can bind to actin.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC5036774&req=5

f6-7_21: Match-mismatch theory of stretch activation. The diagram shows the relations among 6 thin filaments (pink lines) surrounding a thick filament, the positions of target zones on the thin filament (red circles) and the positions of myosin heads (dots). Myosin heads bound to actin are represented as green circles. In (a) most of myosin heads are unable to bind to actin, but after a ~20-nm stretch, many myosin heads can bind to actin.
Mentions: The ability of SA, as mentioned above, is considered essential for the asynchronous operation of IFM, and many investigators have pursued its molecular mechanism. The characteristically high regularity of protein arrangement led to the proposal of the “match-mismatch hypothesis10”, which assumes that a stretch brings actin and myosin into right geometry for interaction. In general, only a limited number of actin monomers on a thin filament are suitably oriented for interaction with myosin heads. These monomers are clustered in small areas called “target zones”. The target zones on the 6 thin filaments surrounding a thick filament are helically arranged (Fig. 6). At a certain sarcomere length, none of the myosin heads are close to the target zones. However, a 19-nm stretch of the sarcomere will bring the myosin heads close enough to interact with actins in the target zones, causing SA.

View Article: PubMed Central - PubMed

ABSTRACT

Insects, the largest group of animals on the earth, owe their prosperity to their ability of flight and small body sizes. The ability of flight provided means for rapid translocation. The small body size allowed access to unutilized niches. By acquiring both features, however, insects faced a new problem: They were forced to beat their wings at enormous frequencies. Insects have overcome this problem by inventing asynchronous flight muscle, a highly specialized form of striated muscle capable of oscillating at >1,000 Hz. This article reviews the structure, mechanism, and molecular evolution of this unique invention of nature.

No MeSH data available.


Related in: MedlinePlus