May have serine protease inhibitor activity (Probable). Might play a role in the glial-neuronal signaling pathway that is important in establishing the electrical properties of axonal membranes (PubMed:10037607). Localizes to longitudinal axon tracts as well as to an axonal scaffold in the brain (PubMed:10037607). A secreted form might exist (Probable). Expressed in the brain and parts of the peripheral nervous system (at protein level) (PubMed:10037607). Expressed from embryonic stage 13 in the differentiating nervous system in a subset of glial cells, including longitudinal glia and segmental boundary cells (PubMed:10037607). Temperature-dependent loss of excitatory junctional potentials in the larval neuromuscular junction.