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 regulation of cell morphology and cytoskeletal organization. Heterodimer of an alpha and a beta subunit. Component of the WASH complex (By similarity). Isoform 2 also is a component of dynactin complex from brain, which contains the actin-related protein ARP1. In cardiac muscle, isoform 1 is located at Z-disks of sarcomeres. In cardiac muscle, isoform 2 is located at sarcomere intercalated disks. Isoform 1 is detected in pectoral muscle, cardiac muscle and gizzard. Isoform 2 is detected in brain and liver (at protein level). Isoform 2 is the predominant isoform of nonmuscle tissues and isoform 1 is the predominant isoform of muscle tissues. Belongs to the F-actin-capping protein beta subunit family.