Protein-protein interactions of proteolytic fragments of actin

Proteolytic fragments of actin, prepared by removal of up to sixty-eight residues from the N-terminal end of the molecule, can form filamentous structures after denaturation in urea solution. The filaments have a diameter similar to F-actin filaments and interact with myosin and tropomyosin. A fragment comprising residues 1 to 207 of the actin sequence did not form filaments or interact with myosin after the urea treatment.