Post-translational phosphorylation of proteodermatan sulfate.

In cultured human skin fibroblasts, the core protein of the small proteodermatan sulfate becomes phosphorylated post-translationally but before the glycosaminoglycan chains are synthesized. This phosphorylation can occur when the intracellular transport is inhibited by carbonyl cyanide m-chlorophenylhydrazone or when the attachment of asparagine-linked oligosaccharides is prevented by tunicamycin. Serine and glycosaminoglycan chains were identified as phosphorylation sites of secreted proteodermatan sulfate. Upon alkaline borohydride treatment and degradation by chondroitin ABC lyase, the main phosphorylated product co-chromatographed with an unsulfated 3H-labeled hexasaccharide prepared analogously from [3H]galactose/[35S]sulfate-labeled proteodermatan sulfate.