putative colanic acid biosynthesis glycosyl transferase WcaC and similar proteins. This family is most closely related to the GT4 family of glycosyltransferases. Escherichia coli WcaC has been predicted to function in colanic acid biosynthesis. WcfI in Bacteroides fragilis has been shown to be involved in the capsular polysaccharide biosynthesis.
Glycosyl transferases group 1. Mutations in this domain of PIGA lead to disease (Paroxysmal Nocturnal haemoglobinuria). Members of this family transfer activated sugars to a variety of substrates, including glycogen, Fructose-6-phosphate and lipopolysaccharides. Members of this family transfer UDP, ADP, GDP or CMP linked sugars. The eukaryotic glycogen synthases may be distant members of this family.
beta-diglucosyldiacylglycerol synthase and similar proteins. beta-diglucosyldiacylglycerol synthase (processive diacylglycerol beta-glucosyltransferase EC 2.4.1.315) is involved in the biosynthesis of both the bilayer- and non-bilayer-forming membrane glucolipids. This family of glycosyltransferases also contains plant major galactolipid synthase (chloroplastic monogalactosyldiacylglycerol synthase 1 EC 2.4.1.46). Glycosyltransferases catalyze the transfer of sugar moieties from activated donor molecules to specific acceptor molecules, forming glycosidic bonds. The acceptor molecule can be a lipid, a protein, a heterocyclic compound, or another carbohydrate residue. The structures of the formed glycoconjugates are extremely diverse, reflecting a wide range of biological functions. The members of this family share a common GTB topology, one of the two protein topologies observed for nucleotide-sugar-dependent glycosyltransferases. GTB proteins have distinct N- and C- terminal domains each containing a typical Rossmann fold. The two domains have high structural homology despite minimal sequence homology. The large cleft that separates the two domains includes the catalytic center and permits a high degree of flexibility.