Binds to actin monomers and regulates the organization of the actin cytoskeleton (PubMed:26574597). At high concentrations, profilin prevents the polymerization of actin, whereas it enhances it at low concentrations (PubMed:29861135). At low concentrations, associates with the poly-proline motif of formins to enhance actin filament elongation rate (PubMed:29861135). Binds ACT1, ACT7 and ACT11 and inhibits actin polymerization (PubMed:26578694). Coordinates the stochastic dynamic properties of actin filaments by modulating formin-mediated actin nucleation and assembly during axial cell expansion (PubMed:26574597). Binds G-actin and poly-L-proline in vitro (PubMed:19200149). Inhibits cell growth of various pathogenic fungal strains (PubMed:30056100). May play a role as antifungal proteins in the defense system against fungal pathogen attacks (PubMed:30056100). Occurs in many kinds of cells as a complex with monomeric actin in a 1:1 ratio. Probably associated with cytoplasmic actin filaments. Expressed at low levels roots, leaves, stems, flowers and siliques (PubMed:8771785, PubMed:8685262). Expressed in leaf epidermal cells, trichomes and stem epidermal cells (PubMed:19200149). Detected in phloem exudates (at protein level) (PubMed:30056100). Down-regulated by light. Delayed germination (PubMed:11340190). In young seedlings, excessive numbers of root hairs, abnormal raised cotyledons, elongated hypocotyls, and elongated cells in the hypocotyl (PubMed:11340190, PubMed:26574597). Defects in rosette leaf and inflorescence development (PubMed:26160044). Causes an allergic reaction in human. Belongs to the profilin family.