InterPro domain: IPR022768

This family consists of several eukaryotic fascin or singed proteins. The fascins are a structurally unique and evolutionarily conserved group of actin cross-linking proteins. Fascins function in the organisation of two major forms of actin-based structures: dynamic, cortical cell protrusions and cytoplasmic microfilament bundles. The cortical structures, which include filopodia, spikes, lamellipodial ribs, oocyte microvilli and the dendrites of dendritic cells, have roles in cell-matrix adhesion, cell interactions and cell migration, whereas the cytoplasmic actin bundles appear to participate in cell architecture [ 1 ]. Dictyostelium hisactophilin, another actin-binding protein, is a submembranous pH sensor that signals slight changes of the H+ concentration to actin by inducing actin polymerisation and binding to microfilaments only at pH values below seven [ 2 ]. Members of this family are histidine rich, typically contain the repeated motif of HHXH [ 2 ].

1. Fascins, and their roles in cell structure and function. Bioessays 24, 350-61
2. Structure of hisactophilin is similar to interleukin-1 beta and fibroblast growth factor. Nature 359, 855-8