Regulation of chondroitin sulfate synthesis: effect of. beta. -xylosides on synthesis of chondroitin sulfate proteoglycan, chondroitin sulfate chains, and core protein
Monolayer cultures of embryonic chick chondrocytes were incubated with /sup 35/SO/sub 4//sup 2 -/ in the presence and absence of 1.0 mM p-nitrophenyl-..beta..-D-xyloside for 2 days. The relative amounts of chondroitin sulfate proteoglycan and free polysaccharide chains were measured following gel filtration on Sephadex G-200. Synthesis of ..beta..-xyloside-initiated polysaccharide chains was accompanied by an apparent decrease in chondroitin sulfate proteoglycan production by the treated cultures. When levels of cartilage-specific core protein were determined by a radioimmunoassay, similar amounts of core protein were found in both ..beta..-xyloside and control cultures, indicating that decreased synthesis of core protein is not responsible for the observed decrease in chondroitin sulfate proteoglycan production. Activity levels of the chain-initiating glycosyltransferases (UDP-D-xylose:core protein xylosyltransferase and UDP-D-galactose:D-xylose galactosyltransferase) as well as the extent of xylosylation of core protein were found to be similar in cell extracts from both culture types. Furthermore, ..beta..-xylosides did not inhibit the xylosyltransferase reaction in cell-free studies. In contrast, the ..beta..-xylosides effectively competed with several galactose acceptors, including an enzymatically synthesized xylosylated core protein acceptor, in the first galactosyltransferase reaction.
- Research Organization:
- Univ. of Chicago
- OSTI ID:
- 5140441
- Journal Information:
- J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 252:18; ISSN JBCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
560305* -- Chemicals Metabolism & Toxicology-- Vertebrates-- (-1987)
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMINES
ANIMALS
BIOSYNTHESIS
BIRDS
CARBOHYDRATES
CHICKENS
CHONDROITIN
FOWL
HYDROGEN COMPOUNDS
INORGANIC ACIDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
METABOLISM
MUCOPOLYSACCHARIDES
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
POLYSACCHARIDES
PROTEINS
RADIOASSAY
RADIOIMMUNOASSAY
SACCHARIDES
SULFATES
SULFUR COMPOUNDS
SULFURIC ACID
SYNTHESIS
TRACER TECHNIQUES
VERTEBRATES