Figure 7. Sulfs are major regulators of 6S within HS.
The addition of 6S to the nascent HS chain within the Golgi is mediated by a family of 6-O-sulfotransferases. Our data suggest that these modifications are fairly extensive throughout the chain (leading to approx. 40% of disaccharides containing 6S groups). It is the activity of the mSulf enzymes that reduces this level to the approx. 15%, which is found in HS prepared from tissues and which finalizes the complex sulfate patterning observed on mature HS chains.