EC 2.4.2.62     
Accepted name: xylosyl α-1,3-xylosyltransferase
Reaction: UDP-α-D-xylose + [protein with EGF-like domain]-3-O-[α-D-xylosyl-(1→3)-β-D-glucosyl]-L-serine = UDP + [protein with EGF-like domain]-3-O-[α-D-xylosyl-(1→3)-α-D-xylosyl-(1→3)-β-D-glucosyl]-L-serine
Other name(s): XXYLT1 (gene name)
Systematic name: UDP-α-D-xylose:[EGF-like domain protein]-3-O-[α-D-xylosyl-(1→3)-β-D-glucosyl]-L-serine 3-α-D-xylosyltransferase (configuration-retaining)
Comments: The enzyme, found in animals and insects, is involved in the biosynthesis of the α-D-xylosyl-(1→3)-α-D-xylosyl-(1→3)-β-D-glucosyl trisaccharide on epidermal growth factor-like (EGF-like) domains. When present on Notch proteins, the trisaccharide functions as a modulator of the signalling activity of this protein.
References:
1.  Minamida, S., Aoki, K., Natsuka, S., Omichi, K., Fukase, K., Kusumoto, S. and Hase, S. Detection of UDP-D-xylose: α-D-xyloside α 1-→3xylosyltransferase activity in human hepatoma cell line HepG2. J. Biochem. 120 (1996) 1002–1006. [PMID: 8982869]
2.  Sethi, M.K., Buettner, F.F., Ashikov, A., Krylov, V.B., Takeuchi, H., Nifantiev, N.E., Haltiwanger, R.S., Gerardy-Schahn, R. and Bakker, H. Molecular cloning of a xylosyltransferase that transfers the second xylose to O-glucosylated epidermal growth factor repeats of notch. J. Biol. Chem. 287 (2012) 2739–2748. [PMID: 22117070]
3.  Yu, H., Takeuchi, M., LeBarron, J., Kantharia, J., London, E., Bakker, H., Haltiwanger, R.S., Li, H. and Takeuchi, H. Notch-modifying xylosyltransferase structures support an SNi-like retaining mechanism. Nat. Chem. Biol. 11 (2015) 847–854. [PMID: 26414444]
[EC 2.4.2.62 created 2020]