Glucoside Xylosyltransferase 1 (GXYLT1)

GXYLT1 is a xylosyltransferase (EC 2.4.2.-) that adds the first xylose to O-glucose-modified residues in the epidermal growth factor (EGF) repeats of proteins such as NOTCH1.The deduced 409-amino acid GXYLT1 protein contains a short N-terminal cytoplasmic domain, followed by a transmembrane domain, a stem region, and a large glycosyltransferase domain containing the conserved DxD motif. GXYLT1 and GXYLT2 share about 50% amino acid identity.HPLC analysis showed that the bond formed by GXYLT1 involved an alpha-1,3 linkage. GXYLT1 and GXYLT2 functioned as xylosyltransferases for the glucosylated peptide substrates EGF repeat 1 of factor VII (F7) and EGF repeats 1 through 5 of mouse Notch1.