Glycosyl transferase, family 1 <p>The biosynthesis of disaccharides, oligosaccharides and polysaccharides involves the action of hundreds of different glycosyltransferases. These enzymes catalyse the transfer of sugar moieties from activated donor molecules to specific acceptor molecules, forming glycosidic bonds. A classification of glycosyltransferases using nucleotide diphospho-sugar, nucleotide monophospho-sugar and sugar phosphates (<db_xref db="EC" dbkey="2.4.1.-"/>) and related proteins into distinct sequence based families has been described [<cite idref="PUB00009409"/>]. This classification is available on the CAZy (CArbohydrate-Active EnZymes) web site. The same three-dimensional fold is expected to occur within each of the families. Because 3-D structures are better conserved than sequences, several of the families defined on the basis of sequence similarities may have similar 3-D structures and therefore form 'clans'.</p><p>Proteins containign this domain transfer UDP, ADP, GDP or CMP linked sugars to a variety of substrates, including glycogen, fructose-6-phosphate and lipopolysaccharides. The bacterial enzymes are involved in various biosynthetic processes that includeexopolysaccharide biosynthesis, lipopolysaccharide core biosynthesis and the biosynthesisof the slime polysaccaride colanic acid. Mutations in this domain of the humanN-acetylglucosaminyl-phosphatidylinositol biosynthetic protein are the cause of paroxysmal nocturnal hemoglobinuria (PNH), an acquired hemolytic blood disordercharacterised by venous thrombosis, erythrocyte hemolysis, infections and defective hematopoiesis.</p>