Abstract
The binding of actin filaments to connectin, a muscle elastic protein, was investigated by means of turbidity and sedimentation measurements and electron microscopy. In the presence of less than 0.12M KCl at pH 7.0, actin filaments bound to connectin. Long actin filaments formed bundles. Short actin filaments also aggregated into irregular bundles or a meshwork, and were frequently attached perpendicularly to long bundles. The binding of F-actin to connectin was saturated at an equal weight ratio (molar ratio, 50:1), as determined by a cosedimentation assay. Larger amounts of sonicated short actin filaments appeared to bind to connectin than intact F-actin. Myosin S1-decorated actin filaments did not bind to connectin. The addition of S 1 to connectin-induced actin bundles resulted in partial disaggregation. Thus, connectin does not appear to interfere with actinmyosin interactions, since myosin S 1 binds to actin more strongly than connectin.
