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. Also expressed in male germ cells at the proximal pole of primary spermatocytes in 16 cell-stage morulae, and in the distal parts of the spermatocytes in 32 and 64 cell-stage morulae. In the spermatids of the 128 cell-stage morulae it is expressed at the proximal pole of the elongated nucleus and the distal pole near the base of the flagellae. Expressed in the cytophore, spermatocytes and young spermatids during spermatogenesis. Not expressed in mature sperm. Belongs to the villin/gelsolin family.