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Microfilament-associated Proteins

Microfilaments provide structure to the plasma membrane, form contractile bundles to facilitate cell motility, and are critical for the formation of cell protrusions such as filopodia, lamellapodia, and phagocytic protrusions. Composed of globular Actin monomers (G-Actin), microfilaments are generated when two parallel long filamentous polymers of Actin (F-Actin) associate to form a helical microfilament. During microfilament formation, Actin monomers are added to either end of a growing polymer though all monomers are oriented in the same direction. This directionality gives rise to microfilaments that are polarized such that one end assembles and disassembles faster (plus end) than the other (minus end). This polarity affects the rate and direction of microfilament formation in the cell. Microfilament assembly and disassembly is mediated by external signals as well as through associations with microfilament associated proteins. These proteins serve a range of functions from sequestering Actin monomers to stabilizing or destabilizing microfilaments.