NEU4, also named as LP5125, belongs to a family of glycohydrolytic enzymes, which remove terminal sialic acid residues from various sialo derivatives, such as glycoproteins, glycolipids, oligosaccharides, and gangliosides. It may function in lysosomal catabolism of sialylated glycoconjugates. NEU4 has a broad substrate specificity being active on glycoproteins, oligosaccharides and sialylated glycolipids.