To investigate the translocation of nucleotide-activated sugars from the cytosol across a membrane into the endoplasmatic reticulum or the Golgi apparatus which is an important step in the synthesis of glycoproteins and glycolipids in eukaryotes. The heterologous expression of the recombinant and codon-adapted human GDP-l-fucose antiporter gene SLC35C1 (encoding an N-terminal OmpA-signal sequence) led to a functional transporter protein located in the cytoplasmic membrane of Escherichia coli. The in vitro transport was investigated using inverted membrane vesicles. SLC35C1 is an antiporter specific for GDP-l-fucose and depending on the concomitant reverse transport of GMP. The recombinant transporter FucT1 exhibited an activity for the transport of H-3-GDP-l-fucose with a V-max of 8 pmol/min mg with a K-m of 4 A mu M. The functional expression of SLC35C1 in GDP-l-fucose overproducing E. coli led to the export of GDP-l-fucose to the culture supernatant. The export of GDP-l-fucose by E. coli provides the opportunity for the engineering of a periplasmatic fucosylation reaction in recombinant bacterial cells.