• Five GlcNAc6ST enzymes have been found in humans.
• GlcNAc6ST-1 (CHST2) catalyzes the formation of 6-sulfo sialyl Lewis-X (6-sulfo sLe^X, the major L-selectin ligand on HEV. This is also a major enzyme facilitating C6-GlcNAc sulfation of KS. CHST2 acts at the non-reducing end of GlcNAc(β1-3)Gal(β1-4)GlcNAc(β1-3).
• GlcNAc6ST-2 (CHST4) is expressed on High Endothelial Cells of the lymph node (HEV). Both CHST2 and CHST4 can make 6-sulfo sialyl Lewis-X. It is also involved in the biosynthesis of MECA-79 epitope. CHST4 acts internally on LacNAc substrate.
• GlcNAc6ST-3 (CHST5) is a GlcNAc6ST that is functional in the intestines. It is highly expressed in colon and small intestine. CHST5 does not act to form KS, but it may attach sulfate to C6 on O-glycan core-2 glycan at the non-reducing end. As it is located in the intestines, it does not participate in the formation of the sulfated sLe^X epitope.
• GlcNAc6ST-4/GST-5 (CHST7) is widely expressed in many organs. Less is known about this enzyme. It may contribute to C6 sulfation of GalNAc during chondroitin sulfate biosynthesis.
• GlcNAc6ST-5 (CHST6) is expressed in the cornea, and involved in the sulfation of keratin sulfate GAGs of the eye. The absence of this enzyme results in macular corneal dystrophy.