Artículo
Trans-activity of plasma membrane-associated ganglioside sialyltransferase in mammalian cells
Fecha de publicación:
09/09/2011
Editorial:
American Society for Biochemistry and Molecular Biology
Revista:
Journal of Biological Chemistry (online)
ISSN:
0021-9258
e-ISSN:
1083-351X
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
Gangliosides are acidic glycosphingolipids that contain sialicacid residues and are expressed in nearly all vertebrate cells.They are synthesized at the Golgi complex by a combination ofglycosyltransferase activities followed by vesicular delivery tothe plasma membrane, where they participate in a variety ofphysiological as well as pathological processes. Recently, a numberof enzymes of ganglioside anabolism and catabolism havebeen shown to be associated with the plasma membrane. In particular,it was observed that CMP-NeuAc:GM3 sialyltransferase(Sial-T2) is able to sialylate GM3 at the plasma membrane (ciscatalyticactivity). In this work, we demonstrated that plasmamembrane-integrated ecto-Sial-T2 also displays a trans-catalyticactivity at the cell surface of epithelial and melanoma cells.By using a highly sensitive enzyme-linked immunosorbent assaycombined with confocal fluorescence microscopy, we observedthat ecto-Sial-T2 was able to sialylate hydrophobically or covalentlyimmobilized GM3 onto a solid surface. More interestingly,we observed that ecto-Sial-T2 was able to sialylate GM3exposed on the membrane of neighboring cells by using both theexogenous and endogenous donor substrate (CMP-N-acetylneuraminicacid) available at the extracellular milieu. In addition,the trans-activity of ecto-Sial-T2 was considerably reducedwhen the expression of the acceptor substrate was inhibited byusing a specific inhibitor of biosynthesis of glycolipids, indicatingthe lipidic nature of the acceptor. Our findings provide thefirst direct evidence that an ecto-sialyltransferase is able totrans-sialylate substrates exposed in the plasma membranefrom mammalian cells, which represents a novel insight into themolecular events that regulate the local glycosphingolipidcomposition.
Palabras clave:
GLYCOSYLTRANSFERASES
,
GANGLIOSIDES
,
PLASMA MEMBRANE
,
ECTO SYALYLTRANSFERASES
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Identificadores
Colecciones
Articulos(CIQUIBIC)
Articulos de CENTRO DE INVEST.EN QCA.BIOL.DE CORDOBA (P)
Articulos de CENTRO DE INVEST.EN QCA.BIOL.DE CORDOBA (P)
Citación
Vilcaes, Aldo Alejandro; Torres Demichelis, Vanina Andrea; Daniotti, Jose Luis; Trans-activity of plasma membrane-associated ganglioside sialyltransferase in mammalian cells; American Society for Biochemistry and Molecular Biology; Journal of Biological Chemistry (online); 286; 36; 9-9-2011; 31437-31446
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