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Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays
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Published on: February 4, 2021

Rod phosphorylation favors folding in a catch muscle myosin

L Castellani, C Cohen

    Proceedings of the National Academy of Sciences of the United States of America
    |June 1, 1987
    PubMed

    Insights

    Molluscan catch muscle myosin undergoes phosphorylation, altering its structure and solubility. This phosphorylation influences myosin

    Area of Science:

    • Muscle physiology
    • Biochemistry
    • Molecular biology

    Background:

    • Molluscan catch muscle myosin exhibits unique phosphorylation of its rod domain by an endogenous kinase.
    • Myosin structure typically involves a head and a tail region; molluscan myosin has a longer tail (~1700 A).
    • Unphosphorylated myosin forms filaments with a 145 A axial repeat at low ionic strength.

    Purpose of the Study:

    • To investigate the structural and solubility changes in molluscan catch muscle myosin upon phosphorylation.
    • To compare the folding behavior of molluscan myosin with smooth and nonmuscle myosins.
    • To elucidate potential mechanisms for catch contraction control.

    Main Methods:

    • Biochemical analysis of myosin structure and solubility.
    • Investigation of protein aggregation and dissociation under varying ionic strengths and conditions.
    • Comparative analysis with other myosin types.

    Main Results:

    • Phosphorylation of the myosin rod increases solubility between 0.05 and 0.15 M NaCl.
    • Soluble species include folded dimers (15 S) and folded monomers (10 S), dependent on ionic strength and counterions.
    • ATP addition to unphosphorylated myosin in 0.15 M NaCl also induces monomer solubilization.
    • Similar molecular folding observed in other myosins is linked to light chain phosphorylation.

    Conclusions:

    • Myosin rod phosphorylation is a key regulator of solubility and potential structural transitions in molluscan catch muscle.
    • The observed folding mechanisms provide insights into the regulation of muscle contraction, particularly catch states.
    • Understanding these phosphorylation-dependent changes is crucial for deciphering the unique properties of catch muscle.

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