Antibody against the amino terminus of alpha-actin inhibits actomyosin interactions in the presence of ATP.
Actomyosin interactions in the presence of ATP were examined by using site-specific antibodies directed against the first seven N-terminal residues on skeletal alpha-actin. Fab fragments of these antibodies (S alpha N Fab) inhibited effectively the actin-activated ATPase of myosin subfragment 1 (S-1) at both 5 and 25 degrees C. Binding experiments carried out in the presence of ATP at 5 degrees C revealed that the catalytic inhibition was related to the inhibition of S-1 binding to actin by Fab. At equimolar ratios of Fab to actin, the binding of S-1 to actin and the activated ATPase were inhibited by 75 and 82%, respectively. These results, when contrasted with the small effect of Fab on rigor actomyosin binding, suggest ATP-induced changes at the interface of actin and myosin.
DasGupta
G
G
Department of Chemistry and Biochemistry, University of California, Los Angeles 90024.
Reisler
E
E
D000199:Actins / Q000276:immunology*; D000205:Actomyosin / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D007128:Immunoglobulin Fragments / Q000276:immunology*; D009132:Muscles / Q000378:metabolism
D000199:Actins; D007128:Immunoglobulin Fragments; D000255:Adenosine Triphosphate; D000205:Actomyosin