Tropomyosin inhibits the interaction of F-actin and filamin.

The value of flow birefringence of F-actin was greatly decreased by filamin due to precipitate formation. This precipitate could be dispersed into birefringent filaments by sonication. Tropomyosin inhibited precipitation of F-actin induced by filamin, and no decrease in birefringence occurred when filamin was added to tropomyosin-bound F-actin. Hence it appears that filamin acts on F-actin in non-muscle cells similarly to alpha-actinin.