Chemical energy usage and myosin light chain phosphorylation in mammalian skeletal muscle

1984 ◽  
Vol 5 (1) ◽  
pp. 45-64 ◽  
Author(s):  
Robert J. Barsotti ◽  
Thomas M. Butler
Keyword(s):  
Skeletal Muscle ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Chemical Energy ◽  
Mammalian Skeletal Muscle ◽  
Myosin Light Chain Phosphorylation ◽  
Energy Usage

Myosin light chain phosphorylation-dephosphorylation in mammalian skeletal muscle

1982 ◽  
Vol 242 (3) ◽  
pp. C234-C241 ◽  
Author(s):  
D. R. Manning ◽  
J. T. Stull
Keyword(s):  
Skeletal Muscle ◽  
Light Chain ◽  
Extensor Digitorum Longus ◽  
Myosin Light Chain ◽  
Extensor Digitorum Longus Muscle ◽  
Extensor Digitorum ◽  
Mammalian Skeletal Muscle ◽  
Phosphate Content ◽  
Longus Muscle ◽  
Fast Twitch

Phosphorylation of the myosin light chain 2 (LC2) subunit was examined in rat fast-twitch and slow-twitch skeletal muscles in response to repetitive stimulation at 23 and 35 degrees C and on incubation of fast-twitch skeletal muscle with isoproterenol. After a 1-s tetany at 35 degrees C, LC2 phosphate content in extensor digitorum longus muscle increased rapidly and transiently from 0.21 to 0.51 mol phosphate/mol LC2. This pattern of phosphorylation was similar to that observed at 23 degrees C. Increases in LC2 phosphate content were dependent on the frequency and duration of stimulation. In soleus muscle LC2 phosphate content was minimal following a 1-s tetany but increased markedly following more prolonged tetanies. On incubation of extensor digitorum longus muscle with isoproterenol (20 microM), LC2 phosphate content did not change, whereas phosphorylase a levels increased. A positive correlation existed between LC2 phosphate content and potentiation of peak twitch tension in both types of muscles, suggesting a physiological function for LC2 phosphorylation.

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