EXPRESSION OF HUMAN-CHROMOSOME 19P ALPHA(1,3)-FUCOSYL-TRANSFERASE GENES IN NORMAL-TISSUES - ALTERNATIVE SPLICING, POLYADENYLATION, AND ISOFORMS

The human alpha(1,3)-fucosyltransferase genes FUT3, FUT5, and FUT6 for m a cluster on chromosome 19p13.3. Expression was studied using revers e transcriptase-polymerase chain reaction, rapid amplification of cDNA ends, and Northern analyses, FUT3 and FUT6 were expressed at high lev els, while FUT5 expression was lower and restricted to fewer cell type s. Alternatively spliced transcripts were identified for FUT3 and FUT6 in kidney, Liver, and colon. A 2.37-kilobase pair (kb) FUT3 transcrip t, detected at high levels in kidney and colon, was absent in liver. F UT6 expression was characterized by a 3.5-kb transcript present in kid ney and liver, and a 2.5-kb transcript in colon and liver. Two polyade nylation sites were shown for FUT5, but absence of consensus sequences suggests reduced efficiency for cleavage and polyadenylation. Two pol yadenylation sites were also shown for FUT6, with the alternatively sp liced downstream signal in tissues expressing high levels of FUT6. In these tissues, additional splicing results in isoforms with catalytic domain deletions, No detectable alpha(1,3)- or alpha(1,4)-fucosyltrans ferase activity was found in assays of cells transfected with FUT6 iso form cDNAs, Thus, tissue-specific post-transcriptional modifications a re associated with expression patterns of FUT3, FUT5, and FUT6.