Promotes matrix assembly (By similarity). Involved in the organization of skeletal muscles and in the formation of neuromuscular junctions (PubMed:33559681). Homodimer or homomultimer; disulfide-linked. Mutants primary motor neurons have reduced axonal branching innervating the muscle fibers and secondary motor neurons have aberrant axonal structure. Mutants skeletal muscle show also an abnormal structure with disorganized myofibers and reduced synaptic formation at the neuromuscular junction. They show a progressive impairment of locomotor behavior and have smaller jaws and abnormal cartilage patterning compared to controls.