What is the name of the thin microfilament found in muscle fibers?

The thin microfilament found in muscle fibers is called actin. Actin is a crucial component of the muscle contraction process, as it works alongside myosin, which is the thick filament. During muscle contraction, the interaction between these two types of filaments allows for the sliding mechanism that shortens the muscle fibers and generates force.

Actin forms a helical structure and plays a key role in the overall structure of muscle fibers, providing the framework for muscle contraction. Additionally, actin filaments are involved in various cellular processes, including movement and shape maintenance within cells. This structural and functional significance clarifies why actin is identified specifically as the thin microfilament in comparison to the others listed, which play different roles in muscle function and regulation.