Acts as a actin nucleation factor, remains associated with the slow-growing pointed end of the new filament. Involved in vesicle transport processes providing a novel link between actin organization and intracellular transport.
Belongs to the spire family. Contains 1 KIND domain. Contains 3 WH2 domains.
Binds to actin monomers via the WH2 domain. The Spir-box targets binding to intracellular membrane structures.