Recombinant Human B4GalT1 Protein, CF

beta4GalT1 is one of seven beta1,4 galactosyltransferases that transfer galactose in a beta1,4 linkage to acceptor sugars including GlcNAc, and Glc, and Xyl. By sequence similarity, the beta4GalTs form four groups: beta4GalT1 and beta4GalT2, beta4GalT3 and beta4GalT4, beta4GalT5 and beta4GalT6, and beta4GalT7 (1). beta4GalT1 is unique among the seven enzymes because it can be expressed either as membrane associated form or secreted form (2). The secreted form is restricted to lactating mammary tissues where the enzyme forms a heterodimer with alpha-lactalbumin to catalyze the synthesis of lactose (3). The membrane form can reside either in the Golgi apparatus, where it adds galactose to N-acetylglucosamine residues, or on cell surface, where it functions as a recognition molecule during a variety of cell to cell and cell to matrix interactions, by binding to specific oligosaccharide ligands on opposing cells or in the extracellular matrix (4). The two enzymatic forms result from alternate transcription initiation sites and post-translational processing (5). Defects in beta4GalT1 are the cause of congenital disorder of glycosylation type 2D (CDG2D) (6). The activity of this enzyme has been measured with a phosphatase-coupled method (7).