Peptide competition of actin activation of myosin-subfragment 1 ATPase by an amino terminal actin fragment.
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.
Kögler
H
H
II. Physiologisches Institut, Universität Heidelberg, Germany.
Moir
A J
AJ
Trayer
I P
IP
Rüegg
J C
JC
D000199:Actins / Q000378:metabolism*; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D003488:Cyanogen Bromide; D004789:Enzyme Activation; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D015879:Myosin Subfragments / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism*; D011817:Rabbits; D013050:Spectrometry, Fluorescence
D000199:Actins; D015879:Myosin Subfragments; D010446:Peptide Fragments; D017301:Ca(2+) Mg(2+)-ATPase; D009218:Myosins; D003488:Cyanogen Bromide