The binding of extra C protein to rabbit skeletal muscle myofibrils has been investigated by fluorescence microscopy with fluorescein-labeled C protein or unmodified C protein plus fluorescein-labeled anti-C protein. Added C protein binds strongly to the I bands, which is consistent with its binding to F actin in solution (Moos, C., C. M. Mason, J. M. Besterman, I. M. Feng, and J. H. Dubin. 1978. J. Mol. Biol. 124:571-586). Of particular interest, the binding to the I band is calcium regulated: it requires a free calcium ion concentration comparable to that which activates the myofibrillar ATPase. This increases the likelihood that C protein-actin interaction might be physiologically significant. When I band binding is suppressed, binding in the A band becomes evident. It appears to occur particularly near the M line, and possibly at the edges of the A band as well, suggesting that those parts of the thick filaments that lack C protein in vivo may nevertheless be capable of binding added C protein.
Article| July 01 1981
Fluorescence microscope study of the binding of added C protein to skeletal muscle myofibrils.
Online Issn: 1540-8140
Print Issn: 0021-9525
J Cell Biol (1981) 90 (1): 25–31.
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C Moos; Fluorescence microscope study of the binding of added C protein to skeletal muscle myofibrils.. J Cell Biol 1 July 1981; 90 (1): 25–31. doi: https://doi.org/10.1083/jcb.90.1.25
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