Chondroitin sulfate proteoglycans (CSPGs) are glycoconjugates that consist of a core protein linked to one or more linear chondroitin sulfate (CS) chains. The chains are composed of alternating glucuronic acid and N-acetylgalactosamine that can be variably O-sulfated. CS synthesis occurs in the Golgi apparatus. It starts with the formation of a tetrasaccharide linker on the core protein followed by the alternating addition of glucuronic acid and N-acetylgalactosamine residues, the latter of which can be O-sulfated. CSPGs are then transported to the plasma membrane. D. melanogaster produces two types of CSPGs: one bearing 4-O-sulfated chondroitin and another with non-sulfated chondroitin. (Adapted from PMID:23774590 and FBrf0228609.)