In a previous study, we isolated a Schizosaccharomyces pombe mutant defective in protein galactosylation (Takegawa, K., Tanaka, N., Tabuchi, M. and Iwahara, S. (1996) Biosci. Biochem. Biotech. 60, 1156-1159). From an S. pombe genomic library, we cloned the gms1+ gene which restored the galactosylation of cell wall glycoproteins. Gms1 protein shares significant sequence similarity with human UDP-galactose and murine CMP-sialic acid transporters. The fission yeast strains deleted for the gms1+ gene lacked galactose residues in sell surface glycoproteins and were significantly decreased in UDP-galactose transport activity. These results showed that the gms1+ encodes an UDP-galactose transporter, and this protein appears to be an essential role for the incorporation of UDP-galactose into the lumen of Golgi in s. pombe.