Formin Binding Protein 4 (FNBP4)

Formins are a group of proteins that are involved in the polymerization of actin and associate with the fast-growing end (barbed end) of actin filaments. The structure of formins is mainly conserved in the C-terminal Formin Homology (FH) domains namely FH1, FH2 and the more loosely defined FH3 domain.

Partial sequence of FNBP4/FBP30 was originally isolated in a screen for proteins that interact with formins, proteins involved in murine limb and kidney development. The full length FNBP4/FBP30 was identified in a screen for genes upregulated in irradiated thymocytes. FNBP4/FBP30 bears two WW domains, a domain that resembles the src-homology 3 (SH3) domain and is known to associate with proline-rich motifs.