Function
The protrusion of the cell membrane is fundamental to cell shape change and locomotion. Actin polymerization plays a critical role in this process. The leading edge of motile cells is dominated by thin actin-rich structures called lamellipodia, which exhibit highly dynamic behavior characterized by rapid extension and retraction.
Lamellipodia, filopodia and membrane ruffles are essential for cell motility, the organization of membrane domains, phagocytosis and the development of substrate adhesions.
Many aspects of the mechanism of lamellipodial protrusion are echoed in the intracellular motility of certain bacterial and viral pathogens, such as the bacterium Listeria monocytogenes.
Their formation relies on the regulated recruitment of molecular scaffolds to their tips (to harness and localize actin polymerization), coupled to the coordinated organization of actin filaments into lamella networks and bundled arrays.
Their turnover requires further molecular complexes for the disassembly and recycling of lamellipodium components.
See also
References
Vartiainen MK, Machesky LM. The WASP-Arp2/3 pathway: genetic insights. Curr Opin Cell Biol. 2004 Apr;16(2):174-81. PMID: #15196561#
Wehrle-Haller B, Imhof B. The inner lives of focal adhesions. Trends Cell Biol. 2002 Aug;12(8):382-9. PMID: #12191915#
Small JV, Stradal T, Vignal E, Rottner K. The lamellipodium: where motility begins. Trends Cell Biol. 2002 Mar;12(3):112-20. PMID: #11859023#