Controls reversibly actin polymerization and depolymerization in a pH-sensitive manner. It has the ability to bind G- and F-actin in a 1:1 ratio of cofilin to actin. It is the major component of intranuclear and cytoplasmic actin rods. Required for muscle maintenance. May play a role during the exchange of alpha-actin forms during the early postnatal remodeling of the sarcomere (By similarity). Colocalizes with CSPR3 in the Z line of sarcomeres. The phosphorylation of Ser-24 may prevent recognition of the nuclear localization signal. Belongs to the actin-binding proteins ADF family.