The amino-terminal region of actin (residues 1-44) contains a binding site for myosin subfragment 1 that participates in activating magnesium-dependent myosin ATPase.
Identifies a myosin-binding site on actin; leaves open its role in cardiac contractility pending in vivo validation.
The amino-terminal region of actin participates in the binding of myosin subfragment 1 (S1) during cross-bridge cycling, thereby assisting in the activation of the magnesium-dependent myosin ATPase. Effects of three actin fragments on the magnesium-dependent S1 and acto-S1 ATPase activities in solution were studied. One of the peptides, containing residues actin 1-44, mimicked the S1 ATPase-activating properties of actin and in turn inhibited acto-S1 ATPase both in a concentration-dependent manner. This suggests peptide competition for the actin binding site on myosin. The other fragments, residues actin 1-18 and 82-119, respectively, had no detectable effect on S1- and acto-S1 ATPase activity.
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Kögler et al. (1991) studied this question.
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