INTERACTION OF ALPHA-ACTININ WITH F-ACTIN AND ITS ABOLITION BY TROPOMYOSIN

The interaction of α‐actinin with F‐actin was examined with the use of the viscometric technique under various conditions. α‐Actinin causes the gelation of F‐actin when added both before and after polymerization. The interaction of α‐actinin with F‐actin seems to be much stronger at 0° than at 21°. In the latter case it takes place only when actin is polymerized with 0.1 M KCl, but not with 1 mM MgCl2 or CaCl2. Tropomyosin, when added before α‐actinin, prevents the formation of F‐actin gel, and when added to already formed gel, causes its disappearance. This abolishing effect of tropomyosin is much stronger at 21° than at 0°. The results are discussed in view of the possible competition between tropomyosin and α‐actinin for the binding to F‐actin. Copyright © 1968, Wiley Blackwell. All rights reserved