Regulation of myosin and overall protein degradation in mouse C2 skeletal myotubes.
We compared the breakdown of total cellular protein with that of the contractile protein, myosin, in cultured C2 mouse skeletal myotubes. The degradation of long-lived cellular proteins (which comprise the vast majority of myotube proteins) was inhibited by serum, insulin, and rat insulin-like growth factor-2. A physiological concentration of insulin was effective, but most of the effect of insulin occurred at concentrations well above the physiological range. IGF-2 inhibited protein breakdown at concentrations well within the range of total IGF-2 known to be present in the serum of fetal and neonatal rats. The breakdown of short-lived proteins was not altered by insulin or serum. We measured myosin degradation using a monoclonal antibody directed against myosin heavy chain. The half-life of myosin was 27 hours, and myosin breakdown was not altered by serum withdrawal applies to certain proteins, but not to others.
Gulve
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EA
Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, MA 02115.
Mabuchi
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Dice
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D000818:Animals; D000911:Antibodies, Monoclonal; D002454:Cell Differentiation; D002478:Cells, Cultured; D003470:Culture Media; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology; D051379:Mice; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000166:cytology / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D011994:Recombinant Proteins
D000911:Antibodies, Monoclonal; D003470:Culture Media; D007328:Insulin; D009124:Muscle Proteins; D011994:Recombinant Proteins; D007335:Insulin-Like Growth Factor II; D009218:Myosins