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Polysialic acid, a unique glycan that is developmentally regulated by two polysialyltransferases, PST and STX, in the central nervous system: From biosynthesis to function
Author(s) -
Nakayama Jun,
Angata Kiyohiko,
Ong Edgar,
Katsuyama Tsutomu,
Fukuda Minoru
Publication year - 1998
Publication title -
pathology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.73
H-Index - 74
eISSN - 1440-1827
pISSN - 1320-5463
DOI - 10.1111/j.1440-1827.1998.tb03967.x
Subject(s) - polysialic acid , glycan , central nervous system , biosynthesis , function (biology) , biology , biochemistry , chemistry , neuroscience , microbiology and biotechnology , glycoprotein , enzyme , cell adhesion , cell , neural cell adhesion molecule
Polysialic acid is a developmentally regulated carbohydrate composed of a linear homopolymer of a‐2,a‐linked sialic acid residues. This unique glycan is mainly attached to the neural cell adhesion molecule (N‐CAM) and implicated in many morphogenic events of the neural cells by modulating the adhesive property of N‐CAM. Recently, the cDNA that encodes polysialyltransferase, which is responsible for the polysialylation of N‐CAM, was successfully cloned from three mammalian species. This review focuses on the molecular cloning of human polysialyltransferase, designated PST. it then describes the number of enzymes actually required for the polysialylation of N‐CAM using an in vitro polysialyltransferase assay. Comparisons between PST and another polysialyltransferase, sialyltransferase X (STX), are made and it Is demonstrated that both enzymes can independently form polysiatic acid In vitro , but that during neural development they coordinately but distinctly synthesize polysialic acid on N‐CAM. The role of polysialic acid in the central nervous system is also discussed. Finally, evidence that the two polysialyltransferases, PST and STX, apparently have distinct roles in the development of neural cells is provided by using a neurite outgrowth assay.