The myosin-bound form of protein phosphatase 1 (PP-1M) is the enzyme that dephosphorylates native myosin in skeletal and cardiac muscles

Alexander A K Chisholm, Philip Cohen

    Research output: Contribution to journalArticle

    55 Citations (Scopus)

    Abstract

    The myosin-bound form of protein phosphatase 1 (PP-1M) and the glycogen-bound form (PP-1G) together account for virtually all the phosphatase activity in rabbit skeletal muscle extracts towards native myosin. PP-1M has a 3-fold higher activity towards native myosin than does PP-1G and accounts for at least 60% of the myosin phosphatase activity in rabbit skeletal muscle. PP-1M accounts for 90% of the myosin phosphatase activity in bovine cardiac muscle, where PP-1G is essentially absent. The high activity of PP-1M towards native myosin appears to arise from interaction of the catalytic subunit with the putative myosin-binding subunit, since chymotryptic digestion liberates a catalytic subunit having the same characteristics as that released by limited proteolysis of PP-1G. Protein phosphatase 2A in skeletal and cardiac muscles is very active towards the isolated myosin P-light chain, but ineffective in dephosphorylating native myosin. The results suggest that PP-1M is the enzyme that dephosphorylates myosin in skeletal and cardiac muscle.

    Original languageEnglish
    Pages (from-to)163-169
    Number of pages7
    JournalBBA - Molecular Cell Research
    Volume971
    Issue number2
    DOIs
    Publication statusPublished - 16 Sep 1988

    Keywords

    • Muscle contraction
    • Myosin
    • Protein phosphatase
    • Protein phosphorylation
    • Striated muscle

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