Microfilaments or
actin filaments are the thinnest filaments of the
cytoskeleton, a structure found in the
cytoplasm of
eukaryotic cells. These linear
polymers of
actin subunits are flexible and relatively strong, resisting buckling by multi-piconewton compressive forces and filament fracture by nanonewton tensile forces. Microfilaments are highly versatile, functioning in
cytokinesis,
amoeboid movement, and changes in cell shape. In inducing this
cell motility, one end of the actin filament elongates while the other end contracts, presumably by
myosin II molecular motors. Additionally, they function as part of
actomyosin-driven contractile molecular motors, wherein the thin filaments serve as tensile platforms for myosin's
ATP-dependent pulling action in
muscle contraction and
pseudopod advancement. Microfilaments have a tough, flexible framework which helps the cell in movement.
