<P> Myofibrils are composed of long proteins including actin , myosin , and titin , and other proteins that hold them together . These proteins are organized into thick and thin filaments called myofilaments , which repeat along the length of the myofibril in sections called sarcomeres . Muscles contract by sliding the thick ( myosin ) and thin ( actin ) filaments along each other . </P>
<P> Myofibrils are composed of long proteins including actin , myosin , and titin , and other proteins that hold them together . These proteins are organized into thick and thin filaments called myofilaments , which repeat along the length of the myofibril in sections called sarcomeres . Muscles contract by sliding the thick ( myosin ) and thin ( actin ) filaments along each other . </P>
the thin contractile protein of a muscle cell is known as
the thin contractile protein of a muscle cell is known as
actin
actin