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Troponin I and caldesmon restrict alterations in actin structure occurring on binding of myosin subfragment 1
E Nowak1, Y S Borovikov, M I Khoroshev
1Department of Muscle Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland.
FEBS Letters
|April 9, 1991
Abstract:
The effect of troponin I and caldesmon on phalloidin-rhodamine- and 1,5-IAEDANS-labelled actin in skeletal muscle ghost fibers was investigated by polarized fluorescence. Both these proteins inhibited the structural alterations in the actin monomer and the increase of flexibility of actin filaments occurring on binding of myosin heads, and their effects were potentiated by tropomyosin. This immobilization of the actin filament through troponin I and caldesmon seems to originate from restriction of the relative motions of the two domains within the monomer.