The importance of C-terminal amino acid residues of actin to the inhibition of actomyosin ATPase activity by caldesmon and troponin I.

Proteolytic elimination of three C-terminal amino acid residues from actin weakens its interaction with caldesmon and troponin I and, in consequence, lowers the inhibitory effects of both proteins on actomyosin ATPase activity. These results prove the importance of C-terminal extremity of actin to the overall interaction of this protein with caldesmon and troponin I.