A monomeric protein in the Golgi membrane catalyzes both N-deacetylation and N-sulfation of heparan sulfate.

Recent studies have shown that the rat liver heparan sulfate N-deacetylase/N-sulfotransferase is a glycoprotein encoded by a single polypeptide chain of 882 amino acids. Using radiation inactivation analyses, we have now determined that in rat liver Golgi vesicles the target size for the N-deacetylase is 88 +/- 14 kDa, whereas that of the N-sulfotransferase is 92 +/- 8 kDa. These results, together with previous biochemical and molecular cloning approaches, demonstrate that 1) in rat liver Golgi membranes there exists only on population of molecules expressing both activities, 2) the active protein in the Golgi membrane functions as a monomer, and 3) there is no evidence that a large independent protein acts as a regulator of either activity.