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. May play a role in the formation of epithelial cell junctions. Heterodimer of an alpha and a beta subunit. Component of the WASH complex, composed of F-actin-capping protein subunit alpha (CAPZA1, CAPZA2 or CAPZA3), F-actin-capping protein subunit beta (CAPZB), WASHC1, WASHC2, WASHC3, WASHC4 and WASHC5. Interacts with S100B (By similarity). Interacts with S100A1. Interacts with SH3BP1; recruits CAPZA1 to forming cell junctions. Interacts with CD2AP (By similarity). Directly interacts with CRACD; this interaction decreases binding to actin (By similarity). Belongs to the F-actin-capping protein alpha subunit family.