Evidence for two distinct alpha(1,2)-fucosyltransferase genes differentially expressed throughout the rat colon.

Blood-group-ABH antigens are carbohydrate structures widely distributed in numerous tissues. These structures are fucosylated by an alpha(1,2)-fucosyltransferase. The occurrence of at least two alpha(1,2)-fucosyltransferase genes in the human genome has been strongly suggested by genetic studies, but only one of them has been cloned so far. Specific primers deduced from this human cDNA were used to amplify a fragment of rat genomic DNA (FTA). Screening of a rat colon cDNA library with this probe allowed us to isolate a clearly distinct, but related, cDNA clone (FTB). Both sequences showed considerable sequence similarity to the human alpha(1,2)-fucosyltransferase cDNA previously cloned. Furthermore, cells transfected with these DNA fragments in antisense orientation displayed a decreased alpha(1,2)-fucosyltransferase activity, indicating that they both correspond to fragments of alpha(1,2)-fucosyltransferase genes. Finally, differential expression of these genes was demonstrated in two rat colon-cancer cell lines and throughout the rat colon.