6ej8
From Proteopedia
Human Xylosyltransferase 1 in complex with peptide QEEEGSGGGQGG
Structural highlights
Disease[XYLT1_HUMAN] XYLT1-CDG;Desbuquois syndrome. The disease is caused by mutations affecting the gene represented in this entry. The gene represented in this entry acts as a disease modifier. Function[XYLT1_HUMAN] Catalyzes the first step in biosynthesis of glycosaminoglycan. Transfers D-xylose from UDP-D-xylose to specific serine residues of the core protein. Initial enzyme in the biosynthesis of chondroitin sulfate and dermatan sulfate proteoglycans in fibroblasts and chondrocytes.[1] [AMBP_HUMAN] Inter-alpha-trypsin inhibitor inhibits trypsin, plasmin, and lysosomal granulocytic elastase. Inhibits calcium oxalate crystallization.[2] Trypstatin is a trypsin inhibitor (By similarity).[3] Publication Abstract from PubMedProteoglycans (PGs) are essential components of the animal extracellular matrix and are required for cell adhesion, migration, signaling, and immune function. PGs are composed of a core protein and long glycosaminoglycan (GAG) chains, which often specify PG function. GAG biosynthesis is initiated by peptide O-xylosyltransferases, which transfer xylose onto selected serine residues in the core proteins. We have determined crystal structures of human xylosyltransferase 1 (XT1) in complex with the sugar donor, UDP-xylose, and various acceptor peptides. The structures reveal unique active-site features that, in conjunction with functional experiments, explain the substrate specificity of XT1. A constriction within the peptide binding cleft requires the acceptor serine to be followed by glycine or alanine. The remainder of the cleft can accommodate a wide variety of sequences, but with a general preference for acidic residues. These findings provide a framework for understanding the selectivity of GAG attachment. Structural Basis for the Initiation of Glycosaminoglycan Biosynthesis by Human Xylosyltransferase 1.,Briggs DC, Hohenester E Structure. 2018 Apr 10. pii: S0969-2126(18)30095-9. doi:, 10.1016/j.str.2018.03.014. PMID:29681470[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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