Uridine diphosphate (UDP) glycosyltransferases (UGTs) mediate the transfer of glycosyl residues from activated nucleotide sugars to acceptor molecules (aglycones), thus regulating properties of the acceptors such as their bioactivity, solubility and transport within the cell and throughout the organism. A superfamily of over 100 genes encoding UGTs, each containing a 42 amino acid consensus sequence, has been identified in the model plant Arabidopsis thaliana. A phylogenetic analysis of the conserved amino acids encoded by these Arabidopsis genes reveals the presence of 14 distinct groups of UGTs in this organism. Genes encoding UGTs have also been identified in several other higher plant species. Very little is yet known about the regulation of plant UGT genes or the localization of the enzymes they encode at the cellular and subcellular levels. The substrate specificities of these UGTs are now beginning to be established and will provide a foundation for further analysis of this large enzyme superfamily as well as a platform for future biotechnological applications.
