Xylosyltransferase I (XYLT1)

Xylosyltransferase (XT; EC 2.4.2.26) catalyzes the transfer of UDP-xylose to serine residues within XT recognition sequences of target proteins. A stable secondary structure assumed by XT1 mRNA prevented reverse transcription of the 5-prime untranslated region. The authors determined that the XT1 protein contains at least 827 amino acids and has a calculated molecular mass of at least 91 kD. It has 3 potential N-glycosylation sites and a DxD motif essential for binding nucleotide sugars in glycosyltransferases. Alignment of the XT1 and XT2 proteins with Xt1 and Xt2 from rat liver revealed highly conserved sequences in the central and C-terminal regions of the proteins. RT-PCR detected XT1 expression in all tissues examined, with highest levels in placenta, kidney, and pancreas, and lowest expression in skeletal muscle.