Non diaphanous formin delphilin acts as a barbed end capping protein

•Delphilin has moderately high binding affinity for actin filaments.•Delphilin, a unique formin, does not have actin filament elongation potency.•Delphilin acts as a barbed end capping protein and it stabilizes filamentous actin.

Formins are multi domain proteins present ubiquitously in all eukaryotes from lower fungi to higher vertebrates. Formins are characterized by the presence of formin homology domain-2 (FH2) and formin homology domain-1 (FH1). There are fifteen different formins present in mouse and human. Among these metazoan formins, Delphilin is a unique formin having two PDZ domains at the N-terminus and FH1, FH2 domain at the C-terminus respectively. In this study we observed that Delphilin binds to actin filaments, and Delphilin inhibits actin filament elongation like barbed end capping protein CapZ. In vitro, Delphilin stabilized actin filaments by inhibiting actin filament depolymerisation. Therefore, our study demonstrates Delphilin as an actin-filament capping protein.