Formins are multi-domain proteins that interact with diverse signalling molecules and cytoskeletal proteins, although some formins have been assigned functions within the nucleus. Formins are characterised by the presence of three FH domains (FH1, FH2 and FH3), although members of the formin family do not necessarily contain all three domains PMID:12538772.

This superfamily represents the formin homology 2 (FH2) domain which plays a role in the nucleation of actin filaments; it remains bound to the barbed end of the growing filament. The domain is involved in processive capping of the actin filament, which is based on a structural unit, the FH2 actin bridge, that binds the barbed end and blocks monomer binding and release. In the FH2 dimer, the second bridge element provides functionality that can overcome the inhibitory properties of the first.

PFAM:PF02181,INTERPRO:IPR015425,DOI:10.1038/nature03251