Functional Actin Networks under Construction: The Cooperative Action of Actin Nucleation and Elongation Factors

Cells require actin nucleation factors to catalyze the formation of actin networks and elongation factors to control the rate and extent of actin polymerization. Earlier models suggested that the different factors assemble actin networks independently. However, recent evidence indicates that the assembly of most cellular networks involves multiple nucleation and elongation factors that work in concert. Here, we describe how these different factors cooperate, directly or indirectly, to promote the assembly of functional actin network in cells, both in the cytoplasm and nucleoplasm. We show that, in many cases, multiple factors collaborate to initiate network assembly and growth. The selection of specific sets of key players enables the cells to fine-tune network structure and dynamics, optimizing them for particular cellular functions.