ABSTRACT
Proteoglycans are widely expressed in animal cells. Interactions between negatively charged glycosaminoglycan chains and molecules such as growth factors are essential for differentiation of cells during development and maintenance of tissue organisation. We propose that glycosaminoglycan chains play a role in targeting of proteoglycans to their proper cellular or extracellular location. The variability seen in glycosaminoglycan chain structure from cell type to cell type, which is acquired by use of particular Ser-Gly sites in the protein core, might therefore be important for post-synthesis sorting. This links regulation of glycosaminoglycan synthesis to the post-Golgi fate of proteoglycans.
Xylosides: compounds in which xylose is coupled to a hydrophobic group. Xylosides cross membranes and initiate GAG synthesis, bypassing the need for xylosylated core proteins. The GAGs initiated on xylosides are in almost all cases of the CS type.
