Reaction: ST3GAL3 transfers Neu5Ac to Type 1 chain to form Type 1 MSGG
- in pathway: Lewis blood group biosynthesis
CMP-N-acetylneuraminate-beta-1,4-galactoside alpha-2,3-sialyltransferase (ST3GAL3), located on the Golgi membrane, mediates the transfer of sialic acid (Neu5Ac, N-acetylneuraminic acid) in an α2,3 linkage to the terminal galactose of Gal-beta-1,3-GlcNAc- and Gal-beta-1,4-GalNAc- sequences found on glycoproteins and glycolipids (Kitagawa & Paulson 1993). The product, Type 1 monosialylgalactosylgloboside (Type 1 MSGG) is the precursor to sialyl Lewis a (sLeA) (also known as the CA19-9 antigen), a tumour marker that is used primarily in the management of pancreatic cancer. Increased sialylation has been observed to be associated with malignant transformation and metastasis.
Reaction - small molecule participants:
CMP [Golgi lumen]
Type 1 MSGG [Golgi lumen]
CMP-Neu5Ac [Golgi lumen]
Type 1 chain [Golgi lumen]
Reactome.org reaction link: R-HSA-9603987
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Reaction input - small molecules:
CMP-N-acetyl-beta-neuraminate(2-)
beta-D-Gal-(1->3)-beta-D-GlcNAc-(1->3)-alpha-D-Gal-yl group
Reaction output - small molecules:
cytidine 5'-monophosphate(2-)
Type 1 monosialylgalactosylgloboside
Reactome.org link: R-HSA-9603987