N-acetyllactosamine synthase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: UDP-galactose + N-acetyl-D-glucosamine = UDP + N-acetyllactosamine. [EC:2.4.1.90]

N-acetyllactosamine synthase activity is a crucial enzymatic function involved in the biosynthesis of complex carbohydrates, particularly in the context of glycoproteins and glycolipids. This activity catalyzes the transfer of N-acetylglucosamine (GlcNAc) from UDP-GlcNAc to a β1,4-linked galactose residue, forming the disaccharide N-acetyllactosamine (LacNAc). LacNAc is a fundamental building block for a wide range of complex glycans that decorate cell surfaces, playing diverse roles in cell-cell interactions, immune recognition, and signal transduction.

The enzyme responsible for this activity is known as β1,4-galactosyltransferase (β4GalT), specifically β4GalT1 in mammals. This enzyme exhibits strict substrate specificity, demanding a β1,4-linked galactose as the acceptor and UDP-GlcNAc as the donor molecule. The reaction proceeds via a two-step mechanism involving the formation of a covalent enzyme-substrate intermediate followed by the transfer of GlcNAc to the galactose residue.

N-acetyllactosamine synthase activity is tightly regulated, ensuring proper glycan biosynthesis and maintaining cellular homeostasis. This regulation can involve factors like enzyme expression levels, substrate availability, and post-translational modifications. Dysregulation of this activity has been linked to various diseases, including cancer and autoimmune disorders, highlighting the critical role of N-acetyllactosamine synthase in maintaining cellular function and health.'
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Proteins (1)

Compounds (1)