BIOL 103 Lecture Notes - Lecture 9: Cell Membrane, Santa Barbara City College, Chemical Equilibrium
Document Summary
Holding onto the substrate, building a network in one area of the cell, and deconstructing the network in another area requiring several abps. The act of forming the protrusion, through the formation of the lamellipodium, requires actin polymerization directly underneath the plasma membrane so that the membrane at the leading edge can be pushed forward. Actin must be depolymerized as the membrane moves forward, near the rear of the network so the cell continues to have access to free actin for polymerization and that the network doesn"t exist beyond its usefulness. Nucleation of new actin filaments mediated by arp complexes at front of the web, newly formed filaments attach to the sides of pre-existing filaments elongating the filaments and push plasma membrane forward. Actin filament ends become protected by capping proteins preventing further assembly or disassembly from old plus ends at front of the array.
