Gangliosides, sialic acid-containing glycosphingolipids, are present in surface membranes of cells and play important functional roles in regulating a wide range of biological processes including cell surface interactions, cell differentiation, and transmembrane signaling. Plasma membrane-associated ganglioside sialidase (NEU3) has been suggested to play essential roles in regulation of cell surface functions because of its major localization in the plasma membrane and strict substrate preference for gangliosides, thought to play important roles in cell surface events through modulation of gangliosides.