Activity and tissue distribution of splice variants of alpha6-fucosyltransferase in human embryogenesis.
The product of the FUT8 gene transfers an alpha1-6 fucose on the innermost N-acetylglucosamine of the chitobiose core of N-glycans. Northern blot analysis shows four main transcripts of 3.0, 3.3, 3.9, and 4.2 kb in the embryo. The larger forms around 4-kb decrease in fetus and adult. Fourteen embryo transcripts of FUT8 were cloned. Twelve exons comprising two new 5'untranslated-exons (A and B) and two new 3'UT-ends (L1 and L2) and the complete genomic organization of the FUT8 gene (330 kb) are described. Transcripts starting with the 5'UT-exon A are always associated with exons C and D. Exon B initiates another series of transcripts associated to exon C and D or directly to exon D. A third series of transcripts starts at exon C. The data suggest an expression of FUT8 regulated by three different promoters, starting transcription in exons A, B, or C. The A or C series are better expressed than the B series. After transfection with these cDNA constructs the transcripts with 5'UT-exons A or C have higher expression of FUT8 transcripts and higher alpha6-fucosyltransferase activity, whereas the activity of the B series is about two-thirds lower for both parameters, suggesting that exon B reduces the expression of the transcripts.
D000328:Adult; D017398:Alternative Splicing / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D005314:Embryonic and Fetal Development / Q000502:physiology*; D005091:Exons; D005647:Fucosyltransferases / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D014644:Genetic Variation; D049452:Green Fluorescent Proteins; D006801:Humans; D007700:Kinetics; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D009928:Organ Specificity; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics*
D017931:DNA Primers; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D005647:Fucosyltransferases; C031692:galactoside 3-fucosyltransferase; C020559:Glycoprotein 6-alpha-L-fucosyltransferase