Encodes a brassinosteroid sulfotransferase. In vitro experiements show that this enzyme has a preference for 24-epibrassinosteroids, particularly 24-epicathasterone, but does not act on castasterone and brassinolide. It also shows sulfating activity toward flavonoids. It is differentially expressed during development, being more abundant in young seedlings and actively growing cell cultures. Expression is induced in response to salicylic acid and methyl jasmonate and bacterial pathogens.
Sulfotransferase that utilizes 3'-phospho-5'-adenylyl sulfate (PAPS) as sulfonate donor to catalyze the stereospecific sulfate conjugation of 24-epibrassinosteroids. Preferred substrates are 24-epicathasterone and 6-deoxo-24-epicathasterone. Low activity with 22-deoxy-24-epiteasterone. No activity with 24-epimers catasterone and brassinolide. Sulfonates salicylic acid. May be involved in detoxification. Enhances plant response to pathogen infection and contributes to long distance signaling in systemic acquired resistance (SAR).