actin-binding protein any of several proteins that associate with either actin monomers or actin filaments in cells and modify their properties. Many of these proteins are found in the cell cortex, an actin-rich layer just below the plasma membrane. Examples include dystropin, profilin, spectrin and ankyrin, fimbrin and a-actinin (see actinin), filamin, gelsolin, and the myosins. The term is sometimes applied specifically to filamin.
