Microfilaments are primarily composed of which protein?

Microfilaments are primarily composed of actin, a globular protein that polymerizes to form long, thin helical structures. Actin filaments are a key component of the cytoskeleton in eukaryotic cells and play vital roles in various cellular processes, including cell shape maintenance, motility, and division. These structures are dynamic, meaning that they can rapidly grow and shrink, allowing cells to respond to their environment effectively.

While myosin is a motor protein that interacts with actin for muscle contraction and movement within cells, it is not a component of microfilaments themselves. Tubulin serves as the building block for microtubules, which are a different part of the cytoskeleton with distinct functions, such as providing structural support and facilitating intracellular transport. Collagen is a structural protein found primarily in the extracellular matrix and connective tissues and does not make up microfilaments. Thus, the correct identification of microfilaments being composed of actin is essential for understanding their role in cellular mechanics and structure.