Reactome | B4GALNT2 transfers GalNAc from UDP-GalNAc to Sial-Gal-GlcNAc-Gal to form the Sd(a) antigen on UMOD

B4GALNT2 transfers GalNAc from UDP-GalNAc to Sial-Gal-GlcNAc-Gal to form the Sd(a) antigen on UMOD

Stable Identifier

R-HSA-8855954

Type

Reaction [transition]

Species

Homo sapiens

Compartment

Golgi membrane, Golgi lumen

ReviewStatus

5/5

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B4GALNT2 transfers GalNAc from UDP-GalNAc to Sial-Gal-GlcNAc-Gal to form the Sd(a) antigen on UMOD

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The histo-blood group antigen Sda was discovered to be a dominant character found in more than 90 % of Caucasian red blood cells. In addition to erythrocytes, the Sda antigen is also found in other tissues and body fluids, particularly in urine of humans and other mammals. The Sda antigen shares a common minimal saccharide structure (GalNAc-beta1-4[Neu5Ac-alpha2-3]Gal-beta-) with the Cad antigen. Both antigens contain a pentasaccharide structure, the Sda antigen's structure being GalNAc-beta1-4[Neu5Ac-alpha2-3]Gal-beta1-4GlcNAc-beta1-3Gal. The last step in the biosynthesis of both Sda and Cad antigens is catalysed by beta-1,4 N-acetylgalactosaminyltransferase 2 (B4GALNT2), a Golgi membrane protein that transfers N-acetylgalactosamine (GalNAc) from UDP-GalNAc to position C4 of the Gal residue of the Neu5Ac-alpha2-3Gal-beta1 sequence (Montiel et al. 2003, Lo Presti et al. 2003, Dall'Olio et al. 2014). Both antigens can be expressed by N- or O-linked chains of glycoproteins. Tamm–Horsfall glycoprotein (THGP, aka UMOD) is a major carrier of the Sda antigen in urine (Soh et al. 1980, Serafini-Cessi & Conte 1982). After proteolytic cleavage, UMOD is secreted into the urine where it may play roles in colloid osmotic pressure, retarding passage of positively charged electrolytes, preventing urinary tract infection and modulateing formation of supersaturated salts and their crystals (Schmid et al. 2010).

Literature References

PubMed ID	Title	Journal	Year
24112972	The expanding roles of the Sd(a)/Cad carbohydrate antigen and its cognate glycosyltransferase B4GALNT2 Dall'Olio, F, Chiricolo, M, Malagolini, N, Trinchera, M, Harduin-Lepers, A	Biochim. Biophys. Acta	2014
14688233	Molecular cloning of the human beta1,4 N-acetylgalactosaminyltransferase responsible for the biosynthesis of the Sd(a) histo-blood group antigen: the sequence predicts a very long cytoplasmic domain Cabuy, E, Dall'Olio, F, Chiricolo, M, Lo Presti, L	J. Biochem.	2003
12678917	Molecular cloning, gene organization and expression of the human UDP-GalNAc:Neu5Acalpha2-3Galbeta-R beta1,4-N-acetylgalactosaminyltransferase responsible for the biosynthesis of the blood group Sda/Cad antigen: evidence for an unusual extended cytoplasmic domain Delannoy, P, Krzewinski-Recchi, MA, Montiel, MD, Harduin-Lepers, A	Biochem. J.	2003
6156677	The relationship between the N-acetylgalactosamine content and the blood group Sda activity of Tamm and Horsfall urinary glycoprotein Morgan, WT, Watkins, WM, Donald, AS, Soh, CP	Biochem. Biophys. Res. Commun.	1980
7072193	Precipitin reaction between Sda-active human Tamm-Horsfall glycoprotein and anti-Sda-serum Conte, R, Serafini-Cessi, F	Vox Sang.	1982
20798515	Uromodulin facilitates neutrophil migration across renal epithelial monolayers Pfaller, W, Bertocchi, C, Jennings, P, Joannidis, M, Prajczer, S, Gruber, LN, Schmid, M, Gandini, R	Cell. Physiol. Biochem.	2010