The major cation directly involved in the interaction of actin and myosin in skeletal muscle is:

The major cation directly involved in the interaction of actin and myosin in skeletal muscle is calcium (Ca++). Calcium binds with troponin to cause tropomyosin to uncover the active sites on the actin filaments so that the myosin heads can attach to form cross bridges. Na+ and K+ are impoant in the mechanism of the action potential. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 5. Excitable Tissue: Muscle. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds),Ganong's Review of Medical Physiology, 24e.