Identification of a Novel Glycosaminoglycan Core-like Molecule II

Salimath, P. V. and Spiro, Robert C. and Hudson, H. Freeze (1995) Identification of a Novel Glycosaminoglycan Core-like Molecule II. Journal of Biological Chemistry, 270 (16). pp. 9164-9168.

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Abstract

The accompanying article (Manzi, A., Salimath, P. V., Spiro, R. C., Keifer, P. A., and Freeze, H. H. (1995) J. Biol. Chem. 270, 9154-9163) reported the complete structure of a novel molecule made by human melanoma cells incubated with 1 m M 4-methylumbelliferyl-Xyl (XylMU). The product resembles a common pentasaccharide core region found in chondroitin/dermatan sulfate glycosaminoglycans, except that a terminal -GalNAc residue is found in a location normally occupied by -GalNAc in these chains or -GlcNAc in heparan sulfate chains. In this paper we show that several other human cancer cell lines and Chinese hamster ovary cells also make -GalNAc-capped xylosides. The [6-H]galactose-labeled XylMU product binds to immobilized -GalNAc-specific lectin from Helix pomatia and the binding is competed by GalNAc, but not by Glc. Binding to the lectin is destroyed by digestion with - N-acetylgalactosaminidase, but not -hexosaminidase. The nature of the aglycone influences the amount and relative proportion of this material made, with p-nitrophenyl--xyloside being a better promoter of -GalNAc-terminated product than XylMU. This novel oligosaccharide accounts for 45-65% of xyloside-based products made by both human melanoma and Chinese hamster ovary cells when they are incubated with 30 µ M XylMU, but at 1 m M both the total amount and the proportion decreases to only 5-10%. In both cell lines this product is replaced by a corresponding amount of Sia2,3Gal4XylMU. Preferential synthesis of the -GalNAc-capped material at very low xyloside concentration argues that it is a normal biosynthetic product and not an experimental artifact. This pentasaccharide may be a previously unrecognized intermediate in glycosaminoglycan chain biosynthesis. Since this -GalNAc residue occurs at a position that determines whether chondroitin or heparan chains are added to the acceptor, it may influence the timing, type, and extent of further chain elongation.

Item Type:	Article
Uncontrolled Keywords:	Glycosaminoglycan
Subjects:	500 Natural Sciences and Mathematics > 07 Life Sciences > 03 Biochemistry & Molecular Biology > 16 Protein Biochemistry
Divisions:	Dept. of Biochemistry
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	09 Jan 2008 07:18
Last Modified:	28 Dec 2011 09:32
URI:	http://ir.cftri.res.in/id/eprint/1622

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