Molecular cloning, expression, chromosomal assignment, and tissue-specific expression of a murine α-(1,3)-fucosyltransferase locus corresponding to the human ELAM-1 ligand fucosyl transferase

Terminal Fucα2-3GlcNAc moieties are displayed by mammalian cell surface glycoconjugates in a tissue-specific manner. These oligosaccharides participate in selectin-dependent leukocyte adhesion and have been implicated in adhesive events during murine embryogenesis. Other functions for these molecules remain to be defined, as do the tissue-specific expression patterns of the corresponding α-(1-3)-fucosyltransferase (α1-3FT) genes. This report characterizes a murine α1-3FT that shares 77% amino acid sequence identity with human ELAM ligand fucosyltransferase (ELFT, also termed Fuc-TIV). The corresponding gene maps to mouse chromosome 9 in a region of homology with the Fuc-TIV locus on human chromosome 11q. In vitro, the murine α1-3FT can efficiently fucosylate the trisaccharide Galα1-3Galβ1-4GlcNAc (apparent K(m) of 0.71 mM) to form an unusual tetrasaccharide (Galα1-3Ga1β1- 4[Fucα1-3]GlcNAc) described in periimplantation mouse tissues. The enzyme can also form the Lewis x determinant from Galβ1-4GlcNAc (K(m) = 2.05 mM), and the sialyl Lewis x determinant from NeuNAcα2-3Galβ1-4GlcNAc (K(m) = 1.78 mM). However, it does not yield sialyl Lewis x determinants when expressed in a mammalian cell line that maintains sialyl Lewis x precursors. Transcripts from this gene accumulate to low levels in hematopoietic organs, but are unexpectedly abundant in epithelia that line the stomach, small intestine, colon, and epididymus. Epithelial cell-specific expression of this gene suggests function(s) in addition to, and distinct from, its proposed role in selectin ligand synthesis.