In the sarcomere, the protein that forms two twisted strands around a central rod-like protein is called actin.
Explanation:
The muscle consists of many proteins like actin, myosin, tropomyosin, nebulin, and titlin in the sarcomeres which help in muscular movement.
Actin is a globular protein with bead-like in appearance. To form the thin filament of the sarcomere, actin molecules attached themselves in a strand or string and get twisted to a helix, which finally look like two twisted pearl strings together. These thin filaments alternate with thick filaments or the myosin in the sarcomere.
The myosin twists like two golf sticks.
