Human Carbohydrate Sulfotransferase 15/CHST15 Antibody

N-Acetylgalactosamine 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST, or, CHST15) is a type II transmembrane protein composed of a short N-terminal cytoplasmic domain and a long C-terminal luminal catalytic domain. GalNAc4S-6ST transfers sulfate from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to the 6-O of GalNAc-4S on chondroitin sulfate A (CS-A), as well as dermatan sulfate (1), generating the chondroitin sulfate E (CS-E) disaccharide unit GlcA beta1-3GalNAc-4S,6S. CS-E binds with strong affinity to Midkine, a heparan sulfate-binding growth factor (2), playing an important regulatory role in differentiation and morphogenesis during embryonic development. In situ hybridization for the expression of GalNAc4S-6ST in the postnatal mouse brain showed a widespread expression of the transcript in the developing brain except at postnatal day 7 (3). For comparison, chondroitin sulfate 6-O sulfotransferase-1 (C6ST-1) encoded by the CHST3 gene, only recognizes and transfers sulfate to the 6-O of unsulfated GalNAc residues on chondroitin sulfate generating the chondroitin sulfate C (CS-C) disaccharide unit GlcA beta1-3GalNAc-6S (4). The sequence of the human GalNAc4S-6ST was found to be the same as human B-cell RAG-associated protein (BRAG) (1).