Sulfation and sulfotransferases 1: Sulfotransferase molecular biology: cDNAs and genes.

Sulfotransferase (ST) enzymes catalyze the sulfate conjugation of many hormones, neurotransmitters, drugs, and xenobiotic compounds. These reactions result in enhanced renal excretion of the sulfate-conjugated reaction products, but they can also lead to the formation of "bioactivated" metabolites. ST enzymes are members of an emerging gene superfamily that presently includes phenol ST (PST), hydroxysteroid ST (HSST), and, in plants, flavonol ST (FST) "families," members of which share at least 45% amino acid sequence identity. These families can be further subdivided into "subfamilies" that are at least 60% identical in amino acid sequence. For example, the PST family includes both PST and estrogen ST (EST) subfamilies. Amino acid sequence motifs exist within ST enzymes that are conserved throughout phylogeny. These signature sequences may be involved in the binding of 3'-phosphoadenosine-5 '-phosphosulfate, the cosubstrate for the sulfonation reaction. There are presently five known human cytosolic ST e...