Mammalian Sialidases and Their Functions

Abstract

Sialidases are glycosidases catalyzing the removal of α-glycosidically linked sialic acid residues from carbohydrate groups of glycoproteins and glycolipids. The removal of sialic acids is the initial step in degradation of such glycoconjugates.However, sialidases of mammalian origin may also be involved in many biological processes other than lysosomal catabolism. Four types of mammalian sialidases have been identified and characterized to date, designated as Neu1, Neu2, Neu3 and Neu4. They differ in major subcellular localization and enzymatic properties including substrate specificity, and each has been found to play a unique role depending on its particular properties. A large body of evidence for their contribution to cellular events including differentiation, growth and apoptosis has now accumulated. The present review attempts to briefly summarize physiological and pathological roles of mammalian sialidases.