Sialic acid

About: Sialic acid is a research topic. Over the lifetime, 10929 publications have been published within this topic receiving 414624 citations. The topic is also known as: (4S,5R,6R,7S,8R)-5-acetamido-4,6,7,8,9-pentahydroxy-2-oxononanoic acid & sialic acid.

Effect of neuraminidase treatment of IgG and alpha 1-acid glycoprotein on their intestinal transport in suckling rats in vivo.

Abstract: Binding and transport of rat immunoglobulin G (IgG), human alpha 1-acid glycoprotein, and their neuraminidase-treated derivatives were studied in vivo in the intestine of suckling rats. IgG and asialo-IgG binding was saturable, preceding active transport; the amounts of gut-associated alpha 1-acid glycoprotein and asialo-alpha 1-acid glycoprotein ("binding") were not saturable; and transport was passive. Binding of asialo-IgG to the intestine was significantly higher than that of native IgG, whereas transport rates were similar. No difference was found for both binding and transport of native and asialo-alpha 1-acid glycoprotein. These results suggest an interaction between the heteroglycan moiety of IgG and its intestinal receptor and exclude a role of sialic acid in the intestinal transport of a heterologous, passively absorbed glycoprotein.

Linkage in rat ascites hepatoma cells

Abstract: Gangliosides in plasma membranes have been assumed to be involved in cellular recognition sites such as receptors of bacterial toxins (van Heyningen et aI., 1971; Cuatrecasas, 1973), viruses (Haywood, 1974; Holmgren et aI., 1980), hormones (Mullin et aI., 1976) and chemical mediators (Woolley and Gommi, 1965). On the other hand, some special gangliosides have been proposed to be regulators of cell growth or differentiation (Bremer et aI., 1984; Tsuji et aI., 1983). Furthermore, alteration of gangliosides associated with oncogenic transformation are well known phenomena (Hakomori, 1984). Since sialic acid of gangliosides plays a key role in these cellular reactions, number of sialic acids, manner of linkage and location of sialyl residues in the back bone structure of gangliosides are thought to be critical for the function of the cells. Sialic acids in ganglioside are attached to the internal or terminal galactose of ganglio-N-tetraose. In the biosynthesis of ganglio series gangliosides, sialic acid is transferred to the galactose moiety of lactosyl-ceramide, then N-acetylgalactosamine and galactose are transferred in stepwise fashion to form GMla. However, in rat ascites hepatoma cells, a biosynthetic pathway of ganglioside via asialogangliosides has been' demonstrated by our structural and metabolic studies (Hirabayashi et aI., 1978; Taki et aI., 1979a). In the tumor cells, N-acetylgalactosamine is preferentially transferred to lactosylceramide and followed by a transfer of galactose to form gangliotetraosylcera-

ST8 Alpha-N-Acetyl-Neuraminide Alpha-2,8-Sialyltransferase 1 (ST8SIA1)

Abstract: The CMP-sialic acid: sialylα2-3Galβ1-4Glcβ1-O-Cer α2,8-sialyltransferase (ST8Sia I) is the key enzyme for the biosynthesis of b-series gangliosides. ST8Sia I catalyses the transfer of a sialic acid residue from CMP-sialic acid onto GM3 (Neu5Acα2-3Galβ1-4Glcβ1-O-Cer) to form GD3 (Neu5Acα2-8Neu5Acα2-3Galβ1-4Glcβ1-O-Cer). The product GD3 can be converted in GT3, and both compounds can be elongated by other monosaccharides (i.e. GalNAc, Gal and sialic acid) to form the b- and c-series gangliosides. Gangliosides from b- and c-series are essentially found in developing tissues during embryogenesis, and mainly restricted to the nervous system in healthy adults. They are enriched in glycolipid-enriched microdomains where they play a key role in the modulation of signal transduction. Moreover, substantial evidences have demonstrated the implication of ST8Sia I and b- and c-series gangliosides in oncogenesis by mediating cell proliferation, migration, tumor growth and angiogenesis.