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Sliding filament theory: A sarcomere in relaxed (above) and contracted (below) positions. The sliding filament theory explains the mechanism of muscle contraction based on muscle proteins that slide past each other to generate movement. [ 1] According to the sliding filament theory, the myosin ( thick filaments) of muscle fibers slide past the ...
Myosins ( / ˈmaɪəsɪn, - oʊ -/ [1] [2]) are a superfamily of motor proteins best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes. They are ATP -dependent and responsible for actin -based motility. The first myosin (M2) to be discovered was in 1864 by Wilhelm Kühne.
Depiction of smooth muscle contraction. Muscle contraction is the activation of tension -generating sites within muscle cells. [ 1][ 2] In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as when holding something heavy in the same position. [ 1]
The Purine Nucleotide Cycle is a metabolic pathway in protein metabolism requiring the amino acids aspartate and glutamate. The cycle is used to regulate the levels of adenine nucleotides, in which ammonia and fumarate are generated. [2] AMP converts into IMP and the byproduct ammonia. IMP converts to S-AMP ( adenylosuccinate ), which then ...
In a cAMP-dependent pathway, the activated G s alpha subunit binds to and activates an enzyme called adenylyl cyclase, which, in turn, catalyzes the conversion of ATP into cyclic adenosine monophosphate (cAMP). [ 5] Increases in concentration of the second messenger cAMP may lead to the activation of. an enzyme called protein kinase A (PKA).
The polypeptide chain then folds and is post-translationally modified. Protein biosynthesis (or protein synthesis) is a core biological process, occurring inside cells, balancing the loss of cellular proteins (via degradation or export) through the production of new proteins. Proteins perform a number of critical functions as enzymes ...
Dystrophin is a protein located between the sarcolemma and the outermost layer of myofilaments in the muscle fiber . It is a cohesive protein, linking actin filaments to other support proteins that reside on the inside surface of each muscle fiber's plasma membrane (sarcolemma). These support proteins on the inside surface of the sarcolemma in ...
Myofilament. Myofilaments are the three protein filaments of myofibrils in muscle cells. The main proteins involved are myosin, actin, and titin. Myosin and actin are the contractile proteins and titin is an elastic protein. The myofilaments act together in muscle contraction, and in order of size are a thick one of mostly myosin, a thin one of ...