Protects actin filaments from depolymerization. Interacts with ACTN2. Interacts with F-actin (By similarity). Colocalizes with actin stress fibers. Expression is restricted to heart and skeletal muscle. Present in intercalated disks of the heart and in the Z-disk region of skeletal muscle (at protein level). By MEF2A in skeletal muscle. By angiotensin II in heart. Xin repeats bind F-actin. Belongs to the Xin family.