How is muscle contraction of striated muscle cells regulated?

Muscle contraction of striated muscle cells is regulated by the proteins troponin and tropomyosin on the actin filaments present in striated muscle cells. 

Striated muscles are made up of repeating sarcomeres composed of alternating long, thin actin filaments and thick myosin filaments overlapping each other. These filaments contain actin and myosin proteins, two contractile proteins that interact with each other causing contractions. Troponin and tropomyosin are two types of regulatory proteins that are responsible for regulating the interaction between actin and myosin and thereby regulating the muscle contraction of the entire striated muscle cell.