Calcium-regulated protein that binds to the plus (or barbed) ends of actin monomers or filaments, preventing monomer exchange (end-blocking or capping). Can promote the assembly of monomers into filaments (nucleation) as well as sever existing filaments. Interacts with actin monomers and filaments. Expressed in circular and longitudinal muscle, pseudohearts, pharynx and gizzard. Not expressed in seminal vesicles. Belongs to the villin/gelsolin family.