B4GalT

B4GALT, short for beta-1,4-galactosyltransferase, refers to a conserved family of enzymes that catalyze the transfer of galactose from UDP-galactose to acceptor sugars to form beta-1,4-glycosidic bonds. In mammals, the B4GALT gene family includes several paralogs, commonly designated B4GALT1 through B4GALT7. These enzymes share a common catalytic mechanism but display tissue-specific expression and substrate preferences, contributing to the biosynthesis and modification of glycoconjugates in the Golgi apparatus.

Most B4GALT enzymes are type II transmembrane proteins with a short cytoplasmic tail, a single transmembrane helix, and a luminal catalytic domain. They typically require divalent cations for activity and use UDP-galactose as the galactose donor. Substrates include N-acetyllactosamine structures on N- and O-glycans, various glycolipids such as lactosylceramide, and, in some family members, proteoglycan linker regions.

Functions attributed to B4GALT enzymes encompass the generation of core glycan structures that influence protein folding, stability, trafficking, and cell–cell interactions, as well as modulation of signaling and immune recognition. Expression and function are studied in the contexts of development, physiology, and disease, with researchers exploring how different paralogs contribute to glycosylation landscapes in tissues and during ontogeny.

Because of their central role in glycosylation, B4GALT genes are of interest in glycobiology and are examined in relation to congenital disorders of glycosylation, cancer biology, and infectious disease, where altered glycosylation patterns may have functional consequences.