INTERACTION OF CALDESMON AND MYOSIN SUBFRAGMENT-1 WITH THE C-TERMINUS OF ACTIN

The interactions of caldesmon and S1 with the C-terminus of actin were examined in co-sedimentation experiments using proteolytically trunctated actin. It is shown that removal of 6 residues from the C-terminus of actin reduces the binding of caldesmon by about 50% while improving the binding of S1 to actin. We also show that S1 protects actin's C-terminus from enzymatic cleavage. Both S1 and caldesmon binding to actin are decreased in the presence of an actin C-terminal peptide. These results emphasize the importance of the C-terminus of actin in binding to S1 and caldesmon. © 1992.