Glycosyltransferase involved in the xylosylation of N-glycans (PubMed:10781814, PubMed:12943552, PubMed:15013764, PubMed:15686448). Possesses beta-1,2-xylosyltransferase activity, transferring xylose from UDP-xylose to the core beta-linked mannose of N-glycans (PubMed:10781814, PubMed:12943552, PubMed:15013764, PubMed:15686448). Involved in the biosynthesis of glycoprotein bound N-glycans (PubMed:15686448, PubMed:22024534). Does not require metal ions for its activity (PubMed:15686448). N(4)-{beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->3)-[beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-beta-D-GlcNAc}-L-asparaginyl-[protein] + UDP-alpha-D-xylose = H(+) + N(4)-{beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->3)-[beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->6)]-[beta-D-Xyl-(1->2)]-beta-D-Man-(1->4)-beta-D-GlcNAcl-(1->4)-beta-D-GlcNAc}-L-asparaginyl-[protein] + UDP Protein modification; protein glycosylation. Localizes in medial cisternae of Golgi apparatus. Glycosylation at least at one of the two sites Asn-51 and Asn-301 is necessary for enzyme stability and activity. Renders plant glycoproteins immunogenic and allergenic in human. This is due to the presence of beta-1,2-xylose and/or core alpha-1,3-fucose which are not found in mammalian proteins, and which constitute epitopes for carbohydrate-reactive antibodies.