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Myosin light chain phosphorylation and phosphorylaseaactivity in rat extensor digitorum longus muscle

Authors
Journal
Biochemical and Biophysical Research Communications
0006-291X
Publisher
Elsevier
Publication Date
Volume
90
Issue
1
Identifiers
DOI: 10.1016/0006-291x(79)91604-8

Abstract

Abstract Phosphorylation of the 18,500 dalton light chain of myosin and conversion of phosphorylase b to a were examined in relation to isometric tension development. Following a l sec tetanic contraction, light chain phosphate content increased from a pre-tetanic value of 0.10 to 0.75 mol phosphate/mol at 7 sec; phosphorylase a activity (ratio of activity −5′AMP +5′AMP ) increased from 0.03 to 0.42 at 4 sec and decreased to control values within 20 sec. Light chain phosphate content, however, declined much more slowly and correlated to post-tetanic potentiation of peak twitch tension. Our results suggest light chain phosphorylation is not obligatory for contraction but may play a role in post-tetanic potentiation.

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