We measured the activities of α-1,3-mannosyl-glycoprotein β-1, 2-N-acetylglucosaminyltrans-ferase, α-1,6-mannosyl-glycoprotein β-1,2-N-acetylglucosaminyltransferase, β-1,4-mannosyl-glyco-protein β-1,2-xylosyltransferase and glycoprotein 3-α-l-fucosyltransferase in the Golgi fraction of suspension-cultured cells of sycamore (Acer pseudoplatanus L.) using fluorescence-labelled oligosaccharides as acceptor substrates for these transferase reactions. The structures of the pyridylaminated oligosaccharides produced by these reactions were analyzed by two-dimensional sugar mapping using high-performance liquid chromatography. We demonstrated that

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produce by these in vitro reactions. On the basis of these results, we discuss a biosynthetic pathway for xylose containing N-linked oligosaccharides in plant glycoproteins.