F-actin filaments & hundreds of actin-binding proteins provide a dynamic framework to position & move organelles and macromolecules in plant cells. F-actin is formed by the polymerization of 45 kDa G-actin monomers into long polymers. F-actin is the basis for a major cytoskeletal system in plants, animals, fungi, and protists.
F-actin (green) in this Fi3 plant tissue culture cell positions the nucleus (red) and channels macromolecules like mRNA and ribosomes to locations in the cytoplasm.		F-actin (green) controls the position and streaming of chloroplasts (red) in this Arabidopsis leaf cell.

 

1. G-actin is a 45 kDa monomeric protein	5. Hundreds of actin binding proteins (ABPs) bind actin
2. G-actin polymerizes into long F-actin filaments	6. G-actin is sequestered in pools by monomer binding proteins like profilin
3. F-actin filaments are composed of two parallel strands of polymerized monomers	7. F-actin is bound by numerous side binding proteins that crosslink it or cause movement (myosin)
4. The two strands of the actin filament are twisted into a alpha helix	8. Some ABPs help F-actin form thick bundles

Kandasamy et al., 1999b

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