Schizosaccharomyces pombe UDP-galactose transporter: identification of itsfunctional form through cDNA cloning and expression in mammalian cells

The Schizosaccharomyces pombe UDP-galactose transporter cDNA (SpUGT cDNA), encoding the product of the gms1(+) gene which consists of two exon sequenc es separated by a 173-bp intron, was cloned by RT-PCR. Its product, a hydro phobic protein of 353 amino acid residues resembling its human counterpart, was expressed in the Golgi membranes of UDP-galactose transporter-deficien t Lec8 cells, and complemented the genetic defect of the mutant cells. This indicated that SpUGT cDNA encodes the functional S. pombe UDP-galactose tr ansporter. The product of an ORF found in the second exon, which was previo usly assumed to be the S. pombe UDP-galactose transporter, thus represents an inactive, truncated form of the SpUGT protein. (C) 1999 Federation of Eu ropean Biochemical Societies.