Gangliosides are acidic glycosphingolipids that contain one or more sialic acid residues and are particularly prevalent on neuronal cells. Ganglioside GD3 is involved in cell adhesion and the growth of cultured malignant cells. ST8SIA1 is a sialyltransferase that catalyzes the transfer of sialic acid from CMP-sialic acid to GM3 (NeuNAca2-3GalB1-4Glc-Cer) to produce GD3 (NeuNAca2-8NeuNAca2-3GalB1-4Glc-Cer) and GT3 (NeuNAca2-8NeuNAca2-8NeuNAca2 -3GalB1-4Glc-Cer) in a successive manner, therefore the enzyme has both GD3 and GT3 synthase activity. ST8SIA1 is mainly expressed in adult and fetal brain, and its expression is enhanced in melanoma cell lines. Like most known glycosyltransferases, is predicted as a type II transmembrane protein with a short N-terminal cytoplasmic domain and a single-pass transmembrane domain followed by an enzymatic domain in the lumen of the Golgi apparatus. However, recently GD3 synthase activity was demonstrated at the surface of epithelial and melanoma cells, suggesting glycosphingolipid synthesis may occur at the cell membrane. Recombinant ST8SIA1 also showed activity on fetuin from fetal calf serum, when measured using a phosphatase-coupled method. Source: Recombinant corresponding to Tyr49-Ser356 from human ST8SIA1 used to 6-His-tag at C-terminal with at N-terminal CD33 signal peptide, expressed in Chinese Hamster Ovary cell line. Molecular Weight: ~36kD Biological Activity: Measured by its ability to transfer Neu5Ac from CMP-Neu5Ac to fetuin of fetal calf serum. Specific Activity: >15pmol/min/ug Endotoxin: ~1EU/1ug (LAL) Storage and Stability: May be stored at 4C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20C. Aliquots are stable for 6 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
