Catalysis of the reaction: 3'-phosphoadenylyl sulfate + alpha-D-glucosaminyl-(heparan sulfate)(n) = 3-sulfo-alpha-D-glucosaminyl-(heparan sulfate)(n) + adenosine 3',5'-bisphosphate + H+.
isoform/isozyme 3a and 3b (3-OST-3A, 3-OST-3B, HS3ST3A, HS3ST3B)