Catalyzes the transfer of sulfate to position 4 of non-reducing N-acetylgalactosamine (GalNAc) residues in both N-glycans and O-glycans. Required for biosynthesis of glycoprotein hormones lutropin and thyrotropin, by mediating sulfation of their carbohydrate structures. Only active against terminal GalNAcbeta1,GalNAcbeta. Not active toward chondroitin. Optimum pH is 7.2. Predominantly expressed in pituitary gland. In brain, it is expressed in pituitary gland, cerebellum, medulla oblongata, pons, thalamus and spinal cord. Expressed in the epidermis. Expressed at lower level in lung, spleen, adrenal gland, placenta, prostate, testis, mammary gland and trachea. Down-regulated (17-fold) in prion-infected cells. The disease is caused by variants affecting the gene represented in this entry. Belongs to the sulfotransferase 2 family. PubMed:10988300 reports the possible existence of a secreted isoform starting at Met-119. However, they do not provide any experimental evidence.