The N-acetylgalactosamine residue of exogenous G(M2) ganglioside is recycled for glycoconjugate biosynthesis in rat liver

M. Trinchera, R. Ghidoni, L. Greggia, G. Tettamanti

Research output: Contribution to journalArticlepeer-review

Abstract

A metabolic recycling of N-acetylgalactosamine (GalNAc), liberated from exogenous G(M2) ganglioside [nomenclature of Svennerholm (1964) J. Lipid Res. 5, 145-155; IUPAC-IUB recommendations (1977) Lipids 12, 455-468], is demonstrated in rat liver. After the injection of a G(M2) ganglioside isotopically radiolabelled on the terminal GalNAc residue ([GalNAc-3H]G(M2)), the liver retained a large amount of radioactivity distributed among: (1) a glycoprotein/glycosaminoglycan fraction, (2) a ganglioside fraction; and (3) a free-sugar fraction. Furthermore, volatile radioactivity was also found. The relative incorporation in the above fractions was time-dependent. The glycoprotein/glycosaminoglycan fraction contained radioactivity that was located on the GalNAc and GlcNAc residues. The ganglioside fraction was composed of two main families: gangliosides formed by a recycling of the liberated GalNAc, and gangliosides derived by direct utilization of the administered G(M2). The free-sugar fraction contained mainly GalNAc. We suggest that GalNAc, after being released in the course of intra-lysosomal ganglioside catabolism, crosses the lysosomal membrane and passes into the cytosol, where the part not degraded is re-utilized for the biosynthesis of the different glycoconjugate classes.

Original languageEnglish
Pages (from-to)103-106
Number of pages4
JournalBiochemical Journal
Volume266
Issue number1
Publication statusPublished - 1990

ASJC Scopus subject areas

  • Biochemistry

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