Sulfotransferases (SOTs) catalyse the transfer of a sulfate group from 3¢-phosphoadenosine 5¢-phosphosulfate (PAPS) to an appropriate hydroxy group of various substrates with the parallel formation of 3¢-phospho-adenosine 5¢-phosphate. In Arabidopsis thaliana, 18 SOT proteins (AtSOT) have been identified.