What are the thin filaments in a muscle made of?

The thin filaments in a muscle are made of actin protein, which is polymerised into a double helical filament. Each actin monomer has a plus (+) end and a minus (-) end, and the thin filament is assembled with the plus ends of the actin monomers pointing away from the centre of the sarcomere. The thin filament also contains regulatory proteins, such as troponin and tropomyosin, which help to control the interaction of the thin filament with the thick filaments during muscle contraction.