CHST15

Chondroitin sulfate (CS) is a glycosaminoglycan which is an important structural component of the extracellular matrix and which links to proteins to form proteoglycans. Chondroitin sulfate E (CS-E) is an isomer of chondroitin sulfate in which the C-4 and C-6 hydroxyl groups are sulfated. This gene encodes a type II transmembrane glycoprotein that acts as a sulfotransferase to transfer sulfate to the C-6 hydroxal group of chondroitin sulfate. This gene has also been identified as being co-expressed with RAG1 in B-cells and as potentially acting as a B-cell surface signaling receptor. Alternative splicing results in multiple transcript variants encoding distinct isoforms.

Full Name

Carbohydrate Sulfotransferase 15

Function

Sulfotransferase that transfers sulfate from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to the C-6 hydroxyl group of the GalNAc 4-sulfate residue of chondroitin sulfate A and forms chondroitin sulfate E containing GlcA-GalNAc(4,6-SO4) repeating units. It also transfers sulfate to a unique non-reducing terminal sequence, GalNAc(4SO4)-GlcA(2SO4)-GalNAc(6SO4), to yield a highly sulfated structure similar to the structure found in thrombomodulin chondroitin sulfate. May also act as a B-cell receptor involved in BCR ligation-mediated early activation that mediate regulatory signals key to B-cell development and/or regulation of B-cell-specific RAG expression; however such results are unclear in vivo.

Biological Process

Chondroitin sulfate biosynthetic process Source: Reactome
Hexose biosynthetic process Source: UniProtKB

Cellular Location

Golgi apparatus membrane. A small fraction may also be present at the cell surface, where it acts as a B-cell receptor.

Topology

Cytoplasmic: 1-80
Helical: 81-101
Lumenal: 102-561

PTM

Glycosylated.