▪ Abstract Virtually every cell type in metazoan organisms produces heparan sulfate. These complex polysaccharides provide docking sites for numerous protein ligands and receptors involved in diverse biological processes, including growth control, signal transduction, cell adhesion, hemostasis, and lipid metabolism. The binding sites consist of relatively small tracts of variably sulfated glucosamine and uronic acid residues in specific arrangements. Their formation occurs in a tissue-specific fashion, generated by the action of a large family of enzymes involved in nucleotide sugar metabolism, polymer formation (glycosyltransferases), and chain processing (sulfotransferases and an epimerase). New insights into the specificity and organization of the biosynthetic apparatus have emerged from genetic studies of cultured cells, nematodes, fruit flies, zebrafish, rodents, and humans. This review covers recent developments in the field and provides a resource for investigators interested in the incredible dive...

Order out of chaos: assembly of ligand binding sites in heparan sulfate.

Sulfonation is an important reaction in the metabolism of numerous xenobiotics, drugs, and endogenous compounds. A supergene family of enzymes called sulfotransferases (SULTs) catalyze this reaction. In most cases, the addition of a sulfonate moiety to a compound increases its water solubility and decreases its biological activity. However, many of these enzymes are also capable of bioactivating procarcinogens to reactive electrophiles. In humans three SULT families, SULT1, SULT2, and SULT4, have been identified that contain at least thirteen distinct members. SULTs have a wide tissue distribution and act as a major detoxification enzyme system in adult and the developing human fetus. Nine crystal structures of human cytosolic SULTs have now been determined, and together with site-directed mutagenesis experiments and molecular modeling, we are now beginning to understand the factors that govern distinct but overlapping substrate specificities. These studies have also provided insight into the enzyme kinetics and inhibition characteristics of these enzymes. The regulation of human SULTs remains as one of the least explored areas of research in the field, though there have been some recent advances on the molecular transcription mechanism controlling the individual SULT promoters. Interindividual variation in sulfonation capacity may be important in determining an individual’s response to xenobiotics, and recent studies have begun to suggest roles for SULT polymorphism in disease susceptibility. This review aims to provide a summary of our present understanding of the function of human cytosolic sulfotransferases.

Sergei Shevtsov

Papers

Structure and function of sulfotransferases.