Description
General description
Recombinant human Beta-1,4-galactosyltransferase 1 (B4GALT1) is expressed in human HEK 293 cells as a glycoprotein with a calculated molecular mass of 40 kDa. The DTT-reduced protein migrates as a ~55 kDa polypeptide on SDS-PAGE due to glycosylation. This protein is manufactured in human cells, with no serum. The human cells expression system allows human-like glycosylation and folding, and often supports higher specific activity of the protein.
Application
This recombinant B4GALT1 product can be used to study the mode of action of the enzyme, as well as its potential inhibitors. It can also be used as a glycoengineering tool to modify glycoproteins in vitro.
Biochem/physiol Actions
β(1→4) galactosyltransferase 1 (B4GALT1) is a type II membrane-bound glycoprotein that transfers galactose from uridine diphosphate-α-D-galactose (UDP-galactose) to acceptor sugars, such as N-Acetylglucosamine (GlcNAc), in a β(1→4) linkage. B4GALT1 resides in the Golgi apparatus of higher eukaryotic cells.
A major function of B4GALT1 is the addition of β(1→4) linked galactose residues to oligosaccharide acceptors with terminal N-acetylglucosamine residues. This is a late elongation step in the N-glycan processing pathway.B4GALT1 enzymatic activity is widely distributed in the vertebrate kingdom, in both mammals and non-mammals, including avians and amphibians.B4GALT1 enzymatic activity has also been demonstrated in a subset of plants which diverged from animals an estimated 1 billion years ago.B4GALT1 interacts with α-lactalbumin (LA), a protein expressed in the mammary gland during lactation, to form the lactose synthase (LS) complex that transfers galactose from UDP-α-D-Gal to glucose, producing the lactose secreted in milk.Defects in B4GALT1 are the cause of congenital disorder of glycosylation type 2D (CDG2D).Glomerular B4GALT1 expression has been found to be increased in IgA nephropathy. IgA binding and IgA-induced mesangial cell phosphorylation of spleen tyrosine kinase and IL-6 synthesis were inhibited by a panel of β(1→4) galactosyltransferase-specific antibodies, which suggests that IgA binds to the catalytic domain of β(1→4) galactosyltransferase.
Other Notes
One unit is defined as the amount of enzyme required to transfer 1.0 nanomole of galactose from UDP-Gal to glucosamine per minute at pH 7.9, 37 oC.
