CLONING OF A RAT ALPHA-1,3-FUCOSYL-TRANSFERASE GENE - A MEMBER OF THEFUCOSYL-TRANSFERASE-IV FAMILY

We report the cloning of a rat alpha 1,3-fucosyltransferase gene (rFuc -7), isolated from a rat genomic library by a PCR-crosshybridization b ased cloning approach using primers derived from the conserved region of human alpha 1,3-Fuc-T sequences. Comparison of the rFuc-T predicted amino acid sequence with those of previously cloned human and murine fucosyltransferases showed highest degree of homology to murine Fuc-TI V (87% identity) and human Fuc-TIV (78% identity), with lower homology (41-49% identity) to Fuc-TIII, V, VI, and VII. COS-1 cells transfecte d with the rFuc-T gene expressed a fucosyltransferase activity with ty pe 2 (Gal beta 1 --> 4GlcNAc)-containing oligosaccharides and the glyc olipid acceptor neolactotetraosylceramide but only low activity with s ialylated substrates; the SSEA-1/Le(x) antigen was detected in transfe cted cells by immunocytochemistry. Based on these results, we surmise that rFuc-T is a member of the fucosyltransferase IV family. Northern blot analysis with a rFuc-T specific probe indicated a major transcrip t of 4.2 kb most abundantly expressed in rat spleen; minor transcripts of different sizes were detected in several tissues, including rat br ain.