Cytoskeleton

G-Actin is the globular form of actin

it is a monomer

if 4 G-Proteins come together, the polymerization process starts

filamentous actin /fibrous actin

polymeric form of actin

it is linear

can form bundles with other F-Actin Proteins (e.g. in Microvilii)

inside the cell F-Actin is branched, so the force against the membrane is distributed and the membrane can’t get punctured