6-O-sulfation enzyme which catalyzes the transfer of sulfate from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to position 6 of the N-sulfoglucosamine residue (GlcNS) of heparan sulfate. Also transfers sulfate to CDSNS-heparin and performs the crucial step modification in the biosynthesis of anticoagulant heparan sulfate (HSact). Critical for normal neuronal development where it may play a role in neuron branching. May also play a role in limb development. May prefer iduronic acid. 3'-phosphoadenylyl sulfate + alpha-D-glucosaminyl-[heparan sulfate](n) = 6-sulfo-alpha-D-glucosaminyl-[heparan sulfate](n) + adenosine 3',5'-bisphosphate + H(+) Inhibited by dithiothreitol and stimulated by protamine. Optimum pH is 6.3. N-glycosylated. Belongs to the sulfotransferase 6 family.