GGTB2 Antibody – Rabbit Polyclonal

This gene is one of seven beta-1,4-galactosyltransferase (beta4GalT) genes. They encode type II membrane-bound glycoproteins that appear to have exclusive specificity for the donor substrate UDP-galactose; all transfer galactose in a beta1,4 linkage to similar acceptor sugars: GlcNAc, Glc, and Xyl. Each beta4GalT has a distinct function in the biosynthesis of different glycoconjugates and saccharide structures. As type II membrane proteins, they have an N-terminal hydrophobic signal sequence that directs the protein to the Golgi apparatus and which then remains uncleaved to function as a transmembrane anchor. By sequence similarity, the beta4GalTs form four groups: beta4GalT1 and beta4GalT2, beta4GalT3 and beta4GalT4, beta4GalT5 and beta4GalT6, and beta4GalT7. This gene is unique among the beta4GalT genes because it encodes an enzyme that participates both in glycoconjugate and lactose biosynthesis. For the first activity, the enzyme adds galactose to N-acetylglucosamine residues that are either monosaccharides or the nonreducing ends of glycoprotein carbohydrate chains. The second activity is restricted to lactating mammary tissues where the enzyme forms a heterodimer with alpha-lactalbumin to catalyze UDP-galactose + D-glucose <=> UDP + lactose. The two enzymatic forms result from alternate transcription initiation sites and post-translational processing. Two transcripts, which differ only at the 5' end, with approximate lengths of 4.1 kb and 3.9 kb encode the same protein. The longer transcript encodes the type II membrane-bound, trans-Golgi resident protein involved in glycoconjugate biosynthesis. The shorter transcript encodes a protein which is cleaved to form the soluble lactose synthase. [provided by RefSeq, Jul 2008]

B4GALT1: The Golgi complex form catalyzes the production of lactose in the lactating mammary gland and could also be responsible for the synthesis of complex-type N-linked oligosaccharides in many glycoproteins as well as the carbohydrate moieties of glycolipids. Defects in B4GALT1 are the cause of congenital disorder of glycosylation type 2D (CDG2D). CDGs are a family of severe inherited diseases caused by a defect in protein N- glycosylation. They are characterized by under-glycosylated serum proteins. These multisystem disorders present with a wide variety of clinical features, such as disorders of the nervous system development, psychomotor retardation, dysmorphic features, hypotonia, coagulation disorders, and immunodeficiency. The broad spectrum of features reflects the critical role of N-glycoproteins during embryonic development, differentiation, and maintenance of cell functions. Belongs to the glycosyltransferase 7 family. 2 isoforms of the human protein are produced by alternative initiation.

Protein type: EC 2.4.1.90; EC 2.4.1.22; Cell adhesion; Membrane protein, integral; Carbohydrate Metabolism - galactose; Glycan Metabolism - glycosphingolipid biosynthesis - lacto and neolacto series; Cell development/differentiation; Motility/polarity/chemotaxis; EC 2.4.1.38; Glycan Metabolism - keratan sulfate biosynthesis; Glycan Metabolism - N-glycan biosynthesis; Cell surface; Transferase

Chromosomal Location of Human Ortholog: 9p13

Cellular Component: glycocalyx; Golgi apparatus; desmosome; extracellular space; basolateral plasma membrane; brush border membrane; Golgi trans cisterna; integral to membrane; Golgi membrane; membrane; plasma membrane; external side of plasma membrane; filopodium

Molecular Function: beta-N-acetylglucosaminylglycopeptide beta-1,4-galactosyltransferase activity; protein homodimerization activity; N-acetyllactosamine synthase activity; manganese ion binding; lactose synthase activity; cytoskeletal protein binding; beta-tubulin binding; UDP-galactosyltransferase activity; galactosyltransferase activity; alpha-tubulin binding

Biological Process: keratan sulfate metabolic process; extracellular matrix organization and biogenesis; glycosaminoglycan metabolic process; positive regulation of epithelial cell proliferation involved in wound healing; oligosaccharide biosynthetic process; positive regulation of apoptosis involved in mammary gland involution; regulation of acrosome reaction; pathogenesis; lactose biosynthetic process; negative regulation of cell proliferation; development of secondary sexual characteristics; mammary gland development; single fertilization; epithelial cell development; penetration of zona pellucida; cell adhesion; Notch signaling pathway; binding of sperm to zona pellucida; protein amino acid N-linked glycosylation; regulation of cell motility; post-translational protein modification; angiogenesis involved in wound healing; multicellular organism reproduction; cellular protein metabolic process; branching morphogenesis of a tube; keratan sulfate biosynthetic process; carbohydrate metabolic process; galactose metabolic process; protein amino acid N-linked glycosylation via asparagine; leukocyte migration; acute inflammatory response

Disease: Congenital Disorder Of Glycosylation, Type Iid