Enables protein serine/threonine phosphatase inhibitor activity. Involved in several processes, including negative regulation of calcineurin-NFAT signaling cascade; negative regulation of skeletal muscle tissue regeneration; and sarcomere organization. Acts upstream of or within with a positive effect on skeletal muscle fiber adaptation. Located in actin cytoskeleton. Is expressed in diaphragm; heart; musculature; and tongue. Orthologous to human MYOZ1 (myozenin 1). [provided by Alliance of Genome Resources, Apr 2022]