Testosterone sulfotransferase: Evidence in the guinea pig that this reaction is carried out by 3 alpha-hydroxysteroid sulfotransferase

During the course of isolating, characterizing, and cloning estrogen and 3- hydroxysteroid sulfotransferases from the guinea pig adrenal gland, it was noted that cytosolic preparations from this tissue would also sulfonate tes tosterone. Therefore, we set: out to isolate and clone the enzyme that perf orms this reaction. Testosterone sulfotransferase (TST) was isolated from t he guinea Dig adrenal by using the standard procedures of ion exchange, aff inity, and high-performance liquid chromatography. When purified, TST was e xamined by liquid-phase nondenaturing isoelectric focusing, it was found th at the TST activity profile completely overlapped with the activity profile of the 3 alpha-hydroxysteroid sulfotransferase (3 alpha HST) isoform, but not the 3 beta-hydroxysteroid sulfotransferase (3 beta HST) isoform. This f inding was further investigated by overexpressing the cDNAs for 3 alpha HST and 3 beta HST in Escherichia coli and examining the expressed proteins fo r TST activity. This experiment confirmed that 3 alpha HST does indeed func tion as a TST. In addition, 3 alpha HST was also found to sulfonate estradi ol but not estrone, a finding that further suggested that 3 alpha HST may f unction as a general 17 beta-hydroxysteroid sulfotransferase. Published by Elsevier Science Inc.