F-actin-capping-protein subunit beta (CapZ beta) belongs to the F-actin capping protein family, which are characteristic heterodimers, consisting of a α subunit (31-36 kDa) and a β subunit (28-32 kDa), that cap the barbed end of actin filaments within all eukaryotes. Their ability to bind the actin filaments is in a manner independent of Ca2++ and requires the C-terminal end of both subunits for optimal binding. F-actin capping protein subunit beta is contained within the Z-discs of striated muscle, where it functions to inhibit the polymerization and depolymerization of actin. Within vertebrates, there are three isoforms for each of F-actin capping protein subunit beta’s subunits. While there is almost nothing known regarding the β3 subunit, the β1 and β2 isoforms each have distinct role. The isoform β2 is predominantly expressed in non-muscle cells and is found in intercalated discs and the cell periphery, but is not observed at Z-discs. Isoform β1 is more greatly expressed in striated muscle and is localized at the Z-discs. It also contains the COOH-terminal extension necessary for capping the actin.
CAPZB; capping protein (actin filament) muscle Z-line, beta; F-actin-capping protein subunit beta; capZ beta; CAPB; CAPZ; CAPPB; FLJ12274; FLJ44693; MGC104401; MGC129749; MGC129750; DKFZp686K0524; capZ 36/32; capZ B1 and B2; beta-actinin subunit II; actin-capping protein Z (cap-Z) beta subunit; zgc:66149; wu:fk65f06