Binds anionic lipids and gangliosides at acidic pH. Homodimer. Lysosomal and also secreted. Detected in brain, small intestine and in soleus, extensor digitorum longus and white gastrocnemius (at protein level) (PubMed:16954209). Detected in brain and skeletal muscle, and at lower leavels in heart (PubMed:11749721). N-glycosylated; the glycan contains mannose-6-phosphate moieties. Belongs to the ependymin family.