# B3GAT1

## Overview
B3GAT1 is a gene that encodes the enzyme beta-1,3-glucuronyltransferase 1, which is crucial in the biosynthesis of glycosaminoglycans such as chondroitin sulfate and heparan sulfate. These glycosaminoglycans are essential components of the extracellular matrix, impacting tissue structure and function. The enzyme catalyzes the addition of glucuronic acid to the growing glycosaminoglycan chain, a key step in the formation of these complex molecules. Beta-1,3-glucuronyltransferase 1 is not only significant in maintaining the structural integrity of cartilage and the nervous system but also plays a protective role in immune responses by modifying glycan compositions on cell surfaces, which can influence the susceptibility to viral infections (Trimarco2022Cellular). Additionally, the enzyme's activity affects the glycosylation of plasma proteins, which is crucial for various biological processes including metabolism and immune modulation (Huffman2011Polymorphisms).

## Function
B3GAT1, or beta-1,3-glucuronyltransferase 1, encodes an enzyme that plays a crucial role in the biosynthesis of glycosaminoglycans, including chondroitin sulfate and heparan sulfate, which are vital components of the extracellular matrix. This enzyme is specifically responsible for the addition of glucuronic acid to the growing glycosaminoglycan chain, essential for the proper function of various tissues, including cartilage and the nervous system. In the context of cellular glycan modification, B3GAT1 competes with sialyltransferases for substrates, leading to a reduction in sialic acid on the cell surface and an increase in glucuronic acid-containing glycans. This alteration in glycan composition on the cell surface plays a protective role against viral infections by limiting the availability of viral receptors, thereby restricting the entry of viruses such as influenza (Trimarco2022Cellular).

Additionally, B3GAT1's activity has been linked to the modulation of plasma glycoproteins. It adds glucuronic acid to the antennae of these proteins, influencing glycosylation traits in human plasma, which are crucial for various biological processes including metabolism and signaling molecule modulation (Huffman2011Polymorphisms).

## Clinical Significance
B3GAT1 has been implicated in various medical conditions through its role in glycosylation processes. Alterations in the expression of B3GAT1 are associated with mastocytosis, particularly in the context of insect venom allergy (IVA). Studies have shown that lower expression of B3GAT1 in mastocytosis patients correlates with increased sensitivity to insect stings, suggesting a role in modulating immune responses to allergens (Górska2016The). Additionally, B3GAT1 is linked to the biosynthesis of the HNK-1 carbohydrate epitope, which is involved in immune regulation and cytotoxicity. This epitope is expressed on a subset of human lymphocytes, including natural killer cells, and its presence on plasma proteins has been confirmed through mass spectrometry analysis (Huffman2011Polymorphisms).

Furthermore, polymorphisms in the B3GAT1 gene have been associated with variations in human plasma N-glycome, which are critical for proper glycosylation of plasma proteins. Such variations can potentially influence the mechanisms of diseases like cancer, diabetes, and cardiovascular disorders by altering protein glycosylation patterns (Huffman2011Polymorphisms). This highlights the clinical significance of B3GAT1 in contributing to the pathophysiology of various diseases through its enzymatic function and interaction with other cellular components.


## References


[1. (Huffman2011Polymorphisms) Jennifer E. Huffman, Ana Knežević, Veronique Vitart, Jayesh Kattla, Barbara Adamczyk, Mislav Novokmet, Wilmar Igl, Maja Pučić, Lina Zgaga, Åsa Johannson, Irma Redžić, Olga Gornik, Tatijana Zemunik, Ozren Polašek, Ivana Kolčić, Marina Pehlić, Carolien A.M. Koeleman, Susan Campbell, Sarah H. Wild, Nicholas D. Hastie, Harry Campbell, Ulf Gyllensten, Manfred Wuhrer, James F. Wilson, Caroline Hayward, Igor Rudan, Pauline M. Rudd, Alan F. Wright, and Gordan Lauc. Polymorphisms in b3gat1, slc9a9 and mgat5 are associated with variation within the human plasma n-glycome of 3533 european adults. Human Molecular Genetics, 20(24):5000–5011, September 2011. URL: http://dx.doi.org/10.1093/hmg/ddr414, doi:10.1093/hmg/ddr414. (104 citations) 10.1093/hmg/ddr414](https://doi.org/10.1093/hmg/ddr414)

[2. (Trimarco2022Cellular) Joseph D. Trimarco, Sarah L. Nelson, Ryan R. Chaparian, Alexandra I. Wells, Nathan B. Murray, Parastoo Azadi, Carolyn B. Coyne, and Nicholas S. Heaton. Cellular glycan modification by b3gat1 broadly restricts influenza virus infection. Nature Communications, October 2022. URL: http://dx.doi.org/10.1038/s41467-022-34111-0, doi:10.1038/s41467-022-34111-0. (9 citations) 10.1038/s41467-022-34111-0](https://doi.org/10.1038/s41467-022-34111-0)

[3. (Górska2016The) Aleksandra Górska, Marta Gruchała-Niedoszytko, Marek Niedoszytko, Agnieszka Maciejewska, Marta Chełmińska, Marcin Skrzypski, Bartosz Wasąg, Małgorzata Kaczkan, Magdalena Lange, Bogusław Nedoszytko, Ryszard Pawłowski, Sylwia Małgorzewicz, and Ewa Jassem. The role of traf4 and b3gat1 gene expression in the food hypersensitivity and insect venom allergy in mastocytosis. Archivum Immunologiae et Therapiae Experimentalis, 64(6):497–503, April 2016. URL: http://dx.doi.org/10.1007/s00005-016-0397-7, doi:10.1007/s00005-016-0397-7. (16 citations) 10.1007/s00005-016-0397-7](https://doi.org/10.1007/s00005-016-0397-7)