Molecular cloning of a cDNA encoding a novel human leukocyte alpha-1,3-fucosyltransferase capable of synthesizing the sialyl Lewis x determinant.
The sialyl Lewis x determinant (NeuAc alpha 2,3Gal beta 1, 4[Fuc alpha 1,3]GlcNAc) is an essential component of leukocyte counterreceptors for E-selectin and P-selectin. The final step in sialyl Lewis x synthesis is catalyzed by alpha-1,3-fucosyltransferases acting on sialylated glycoconjugate precursors. Cultured human leukocytic cell lines express an alpha-1,3-fucosyltransferase gene termed Fuc-TIV or ELFT but do not express the other three cloned human alpha-1,3-fucosyltransferase genes to any significant degree. The physiological role of Fuc-TIV/ELFT in sialyl Lewis x biosynthesis is uncertain, however, since it can catalyze the synthesis of this determinant in some, but not all, transfected cell lines in a manner that is dependent upon the glycosylation phenotype of the host cell. We report here the molecular cloning of a cDNA encoding a new human leukocyte alpha-1,3-fucosyltransferase, termed Fuc-TVII, capable of synthesizing the sialyl Lewis x moiety. The cDNA sequence predicts a 341-amino acid-long type II transmembrane protein typical of mammalian glycosyltransferases. When expressed in mammalian cells, the Fuc-TVII cDNA directs the synthesis of cell surface sialyl Lewis x moieties but not the Lewis x, Lewis a, sialyl Lewis a, or VIM-2 determinants. Fuc-TVII can efficiently utilize alpha-2,3-sialyllactosamine in vitro to form the sialyl Lewis x tetrasaccharide but does not utilize lactosamine to form the Lewis x moiety. Northern blot analyses show that the Fuc-TVII gene is transcribed in HL-60 cells, a human promyelocytic cell line, and in YT cells, a natural killer-like cell line. Fuc-TVII represents a leukocytic alpha-1,3-fucosyltransferase that can participate in selectin ligand synthesis via its ability to catalyze the synthesis of sialyl Lewis x determinants.
Natsuka
S
S
Howard Hughes Medical Institute, University of Michigan Medical School, Ann Arbor 48109.
Gersten
K M
KM
Zenita
K
K
Kannagi
R
R
Lowe
J B
JB
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002240:Carbohydrate Sequence; D002460:Cell Line; D002522:Chlorocebus aethiops; D002874:Chromosome Mapping; D002880:Chromosomes, Human, Pair 11; D003001:Cloning, Molecular; D006224:Cricetinae; D004247:DNA / Q000235:genetics; D017931:DNA Primers; D018076:DNA, Complementary / Q000378:metabolism; D005647:Fucosyltransferases / Q000096:biosynthesis / Q000097:blood* / Q000235:genetics; D006801:Humans; D007694:Killer Cells, Natural; D015473:Leukemia, Promyelocytic, Acute; D007962:Leukocytes / Q000201:enzymology*; D051379:Mice; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000096:biosynthesis*; D016133:Polymerase Chain Reaction / Q000379:methods; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D000080506:Sialyl Lewis X Antigen; D013379:Substrate Specificity; D014162:Transfection; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D018076:DNA, Complementary; D009844:Oligosaccharides; D011994:Recombinant Proteins; D000080506:Sialyl Lewis X Antigen; D004247:DNA; D005647:Fucosyltransferases; C031692:galactoside 3-fucosyltransferase