Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phosphorylation of decorin was investigated by incubating a rat fibroblast cell line with radiolabelled phosphate and carbohydrate precursors. There was a transient phosphorylation of the linkage-region saccharides in intracellular decorin prior to assembly of the galactosaminoglycan chain. Phosphorylation gradually increased from xylosylated, galactosyl-xylosylated to galactosyl-galactosyl-xylosylated core protein where all trisaccharide stubs were phosphorylated. Addition of the first glucuronate residue was accompanied by rapid dephosphorylation. Brefeldin A treatment resulted in segregation of galactosaminoglycan synthesis and dephosphorylation. Enzymatic degradation of brefeldin-A-arrested immature proteoglycan with incomplete galactosaminoglycan chain [Moses, J., Oldberg, A., Eklund, E. & Fransson, L.-A. (1997) Eur. J. Biochem., in the press] by using chondroitin AC lyase and chondro-glycuronidase, followed by beta-galactosidase treatment, demonstrated the sequence galactosyl-galactosyl-phosphoxylose. The xylose was resistant to direct periodate oxidation, but sensitive after treatment with alkaline phosphatase, showing that the phosphate was located at C2 of xylose. The transient 2-phosphorylation of xylose may be involved in intracellular transport and/or in the control of modifications of the glycan chain.
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PMID:Biosynthesis of the proteoglycan decorin--transient 2-phosphorylation of xylose during formation of the trisaccharide linkage region. 934 11

We have transiently expressed decorin with a C-terminal KDEL endoplasmic reticulum retention signal peptide in COS-7 cells to study initiation of galactosaminoglycan synthesis in the endoplasmic reticulum-Golgi intermediate compartment. All decorin-KDEL molecules were substituted with N-linked oligosaccharides sensitive to endoglycosidase H, indicating that the core protein was located proximal to the medial-Golgi. O-Linked glycosylation was only initiated in a minor fraction of the molecules. The O-linked saccharides were characterized by gel filtration after stepwise degradations using chondroitin ABC/AC-I lyases, beta1-3-glycuronidase, beta-galactosidase, and alkaline phosphatase. The major O-linked saccharide was the linkage region pentasaccharide GalNAcbeta1-4GlcUAbeta1-3Galbeta1-3Galbeta1-4Xyl-2-phosphate, demonstrating initiation of chondroitin synthesis in the endoplasmic reticulum-Golgi intermediate compartment. In the presence of brefeldin A, partial elongation of a chondroitin chain took place, indicating retrieval of polymerases but not of sulfotransferases.
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PMID:Initiation of the decorin glycosaminoglycan chain in the endoplasmic reticulum-Golgi intermediate compartment. 1266 76