Reannealing of phalloidin-treated actin filaments during recovery after sonication and its inhibition by β-actinin

AbstractPhalloidin (2 mol per mol actin)-treated pyrenyl F-actin showed a critical concentration of 1.8 μM in the presence of 10 mM KCl, 0.2 mM ADP, and 5 mM Tris-HCl buffer, pH 8.0 at 25°C. The filament weight concentration did not change at all during and after sonication, yet degrees of flow birefringence increased and the filament number concentration decreased after the termination of sonication. The latter changes were not affected by EDTA, but inhibited by β-actinin. These observations suggest that reannealing of short pieces of phalloidin-treated actin filaments fragmented during sonication takes place during recovery after sonication

Isolation of Nebulin from Rabbit Skeletal Muscle and Its Interaction with Actin

Nebulin is about 800 kDa filamentous protein that binds the entire thin filament of vertebrate skeletal muscle sarcomeres. Nebulin cannot be isolated from muscle except in a completely denatured form by direct solubilization of myofibrils with SDS because nebulin is hardly soluble under salt conditions. In the present study, nebulin was solubilized by a salt solution containing 1 M urea and purified by DEAE-Toyopearl column chromatography via 4 M urea elution. Rotary-shadowed images of nebulin showed entangled knit-like particles, about 20 nm in diameter. The purified nebulin bound to actin filaments to form loose bundles. Nebulin was confirmed to bind actin, α-actinin, β-actinin, and tropomodulin, but not troponin or tropomyosin. The data shows that full-length nebulin can be also obtained in a functional and presumably native form, verified by data from experiments using recombinant subfragments

In vitro Dimerization of I-protein, an A-I Junctional Component of Skeletal Muscle Myofibrils : Biochemistry

Volume: 5Start Page: 347End Page: 35

Calcium-Activated Neutral Protease Quickly Converts α-Connectin to β-Connectin in Chicken Breast Muscle Myofibrils : COMMUNICATION : Biochemistry

Volume: 6Start Page: 797End Page: 80