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Brazilian Journal of Medical and Biological Research

Print version ISSN 0100-879XOn-line version ISSN 1414-431X

Abstract

HANDFORD, M.; RODRIGUEZ-FURLAN, C.  and  ORELLANA, A.. Nucleotide-sugar transporters: structure, function and roles in vivo. Braz J Med Biol Res [online]. 2006, vol.39, n.9, pp.1149-1158. ISSN 0100-879X.  http://dx.doi.org/10.1590/S0100-879X2006000900002.

The glycosylation of glycoconjugates and the biosynthesis of polysaccharides depend on nucleotide-sugars which are the substrates for glycosyltransferases. A large proportion of these enzymes are located within the lumen of the Golgi apparatus as well as the endoplasmic reticulum, while many of the nucleotide-sugars are synthesized in the cytosol. Thus, nucleotide-sugars are translocated from the cytosol to the lumen of the Golgi apparatus and endoplasmic reticulum by multiple spanning domain proteins known as nucleotide-sugar transporters (NSTs). These proteins were first identified biochemically and some of them were cloned by complementation of mutants. Genome and expressed sequence tag sequencing allowed the identification of a number of sequences that may encode for NSTs in different organisms. The functional characterization of some of these genes has shown that some of them can be highly specific in their substrate specificity while others can utilize up to three different nucleotide-sugars containing the same nucleotide. Mutations in genes encoding for NSTs can lead to changes in development in Drosophila melanogaster or Caenorhabditis elegans, as well as alterations in the infectivity of Leishmania donovani. In humans, the mutation of a GDP-fucose transporter is responsible for an impaired immune response as well as retarded growth. These results suggest that, even though there appear to be a fair number of genes encoding for NSTs, they are not functionally redundant and seem to play specific roles in glycosylation.

Keywords : Glycoconjugates; Glycosyltransferases; Golgi apparatus; Nucleotide-sugars; Nucleotide-sugar transporters.

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