Neobiosynthesis of glycosphingolipids by plasma membrane-associated glycosyltransferases

CRESPO P.M.; TORRES DEMICHELIS V.A.; DANIOTTI J.L.

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Lugar: Bethesda; Año: 2010 vol. 285 p. 29179 - 29179

Gangliosides, complex glycosphingolipids containing sialicacids, are synthesized in the endoplasmic reticulum and inthe Golgi complex. These neobiosynthesized gangliosidesmove via vesicular transport to the plasma membrane, becomingcomponents of the external leaflet. Gangliosidescan undergo endocytosis followed by recycling to the cellsurface or sorting to the Golgi complex or lysosomes forremodeling and catabolism. Recently, glycosphingolipid catabolicenzymes (glycohydrolases) have been found to be associatedwith the plasma membrane, where they display activityon the membrane components. In this work, we demonstratedthat ecto-ganglioside glycosyltransferases may catalyzeganglioside synthesis outside the Golgi compartment,particularly at the cell surface. Specifically, we report the firstdirect evidence of expression and activity of CMP-NeuAc:GM3 sialyltransferase (Sial-T2) at the cell surface