Enables phosphatase activity and protein domain specific binding activity. Involved in brain development; dephosphorylation; and intracellular distribution of mitochondria. Located in several cellular components, including cytoplasmic microtubule; perinuclear region of cytoplasm; and ruffle membrane. Is extrinsic component of mitochondrial outer membrane. Is active in presynapse. Orthologous to human SYNJ2 (synaptojanin 2). [provided by Alliance of Genome Resources, Apr 2022]