The function of CHST8 (carbohydrate sulfotransferase 8, Ensembl gene identifier ENSG00000124302) is as follows. Catalyzes the transfer of sulfate to position 4 of non- reducing N-acetylgalactosamine (GalNAc) residues in both N-glycans and O-glycans. Transfers sulfate to the 4-position of GalNAc in the context of GalNAcbeta1->4GlcNAcbeta1->R attached to both N-linked and core 2 branched O-linked oligosaccharides. Required for biosynthesis of glycoprotein hormones lutropin and thyrotropin, by mediating sulfation of their carbohydrate structures (PubMed:10988300, PubMed:11001942, PubMed:11445554, PubMed:28204496). Not active toward chondroitin and dermatan (PubMed:10988300, PubMed:11001942, PubMed:11445554). {ECO:0000269|PubMed:10988300, ECO:0000269|PubMed:11001942, ECO:0000269|PubMed:11445554, ECO:0000269|PubMed:28204496}.