B3GAT1

B3GAT1 Full Name

beta-1,3-glucuronyltransferase 1

B3GAT1 Introduction

The B3GAT1 gene (Beta-1,3-Glucuronyltransferase 1) encodes a critical glycosyltransferase enzyme predominantly expressed in the central nervous system. This enzyme is responsible for the biosynthesis of the HNK-1 carbohydrate epitope (also known as CD57), a specific sulfated glucuronyl-carbohydrate moiety found on glycolipids and glycoproteins. Functionally, B3GAT1 acts by transferring a glucuronic acid residue to the terminal galactose of N-acetyllactosamine. The resulting HNK-1 epitope acts as a recognition signal essential for cell-cell adhesion and migration. In the developing nervous system, this interaction regulates synaptic plasticity, neurite outgrowth, and the migration of neural crest cells. In the immune system, the epitope serves as a marker for the maturation of Natural Killer (NK) cells and T-lymphocytes, modulating their adhesion and cytotoxicity.

Figure 1. Schematic diagram of HNK-1 biosynthesis. (Source: Kawade H, et al. 2021)

The clinical relevance of B3GAT1 is underscored by a rare autosomal recessive disorder known as Baratela-Scott Syndrome (also classified as B3GAT1-CDG, a Congenital Disorder of Glycosylation). This condition arises from loss-of-function mutations in the B3GAT1 gene, leading to a deficiency in the HNK-1 epitope. Patients typically present with a distinct phenotype characterized by skeletal dysplasia (short stature, joint dislocations), facial dysmorphism, congenital heart defects, and cognitive impairment. This highlights the gene's indispensable role in skeletal and cardiac development. Furthermore, because the HNK-1 epitope regulates synaptic architecture, variations in B3GAT1 expression and reduced epitope levels have been linked to susceptibility to psychiatric disorders, particularly Schizophrenia, where disrupted neural connectivity is a core pathological feature.

Alternate Names for B3GAT1

B3GAT1; beta-1,3-glucuronyltransferase 1; NK1; CD57; HNK1; LEU7; NK-1; GLCATP; GLCUATP; galactosylgalactosylxylosylprotein 3-beta-glucuronosyltransferase 1; glcUAT-P; LEU7 antigen; glucuronosyltransferase P; UDP-GlcUA:glycoprotein beta-1,3-glucuronyltransferase;

• 1. Kawade H, et al. Tissue-Specific Regulation of HNK-1 Biosynthesis by Bisecting GlcNAc. Molecules. 2021 Aug 26;26(17):5176.
  2. Dubail J, et al. Chondrodysplasias With Multiple Dislocations Caused by Defects in Glycosaminoglycan Synthesis. Front Genet. 2021 Jun 16;12:642097.