Enables PDZ domain binding activity; identical protein binding activity; and ubiquitin-protein transferase activity. Acts upstream of or within ubiquitin-dependent protein catabolic process. Located in cytoplasm. Is expressed in several structures, including brain; heart; lung; nasal epithelium; and spinal cord. Orthologous to human LNX1 (ligand of numb-protein X 1). [provided by Alliance of Genome Resources, Apr 2022]