May be involved in neural development. Involved in regulation of osteoblast function and bone formation. Involved in matrix vesicle release by osteoblasts; this function seems to involve maintenance of the actin cytoskeleton. May be involved in cellular trafficking of SERT and thereby in regulation of serotonin uptake. Interacts with SERT. Colocalizes with SERT at the plasma membrane. Neurons and glia; cerebellar Bergmann glia, in glia within white matter tracts of the cerebellum and cerebrum, and in embryonic dorsal root ganglia. Belongs to the myelin proteolipid protein family.