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Phosphorylation of rabbit skeletal muscle myosin in situ
Author(s) -
Moore Russell L.,
Houston Michael E.,
Stull James T.,
Iwamoto Gary A.
Publication year - 1985
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041250219
Subject(s) - rabbit (cipher) , myosin , phosphorylation , in situ , skeletal muscle , microbiology and biotechnology , chemistry , biology , anatomy , computer science , computer security , organic chemistry
Myosin light chain (P light chain) is phosphorylated by Ca 2+ . calmodulindependent myosin light chain kinase. Based on studies with rat skeletal muscles, it has been shown that P light chain phosphorylation correlated to the extent of potentiation of isometric twitch tension. It is not clear whether this correlation exists in rabbit skeletal muscle, which has been the primary source of contractile proteins for biochemical studies. Therefore, phosphorylation of myosin P light chain in rabbit slow–twitch soleus and fast‐twitch plantaris muscles in situ was examined. Electrical stimulation (5 Hz, 20 seconds) of plantaris muscle produced an increase in the phosphate content of P light chain from 0.17 to 0.45 mol phosphate/mol P light chain. This increase in phosphate content was accompanied by a 58% increase in maximal isometric twitch tension. Tetanic stimulation (100 Hz, 15 seconds) of rabbit soleus muscle resulted in only a small increase in P light chain phosphate content from 0.02 to 0.10 mol phosphate/mol P light chain, and posttetanic twitch tension did not increase significantly. The correlation between potentiated isometric twitch tension and P light chain phosphorylation in rabbit fast‐twitch muscle is similar to that observed in rat skeletal muscle. These results were consistent with the hypothesis that phosphorylation of rabbit skeletal muscle myosin, which results in an increase in actin‐activated ATPase activity, may be related to isometric twitch potentiation.