Actin bundles are necessary for the formation of specialized cellular processes, intercellular communication, and cell migration. Actin binding proteins guide the reorganization of the cytoskeleton that underlie these processes.
Fascins bundle actin filaments into large, tightly packed hexagonal arrays that support diverse cellular processes including microvillar projections and filopodial extensions at the leading edge of migratory cells and that has been implicated in cell motility in several cell types (Jawhari et al 2003). Fascin should contain two actin binding domains since the protein cross-links actin filaments as a monomer (Cant & Cooley 1995). Fascin is widely expressed throughout human cells including those of the brain, blood, colon, lung, breast, ovary, and testis. In the brain, fascin expression has been localized to neurons, glial cells, and endothelial cells.(Nagai et al. 2008)
Sequence alignment indicates that the members of the fascin family form a distinct class of proteins as they share a high degree of sequence identity with one another, but do not have significant sequence similarities with other known proteins (Tseng et al 2001).One actin binding site is contained within the C-terminal half of fascin. This 21 amino acid region is a highly conserved domain is hydrophobic (Cant & Cooley 1995). Another actin binding region is found to be in the N-terminal region. The consequences of the interaction between fascin-1 and actin are modulated by the interplay of other Actin-binding proteins, but it is still unclear how these interactions are linked functionally to extracelllualr cues (Adams, 2004).