F-actin-capping proteins bind in a Ca(2+)-independent manner to the fast growing ends of actin filaments (barbed end) thereby blocking the exchange of subunits at these ends. Unlike other capping proteins (such as gelsolin and severin), these proteins do not sever actin filaments (By similarity). Heterodimer of an alpha and a beta subunit. Belongs to the F-actin-capping protein beta subunit family.