Testosterone sulfotransferase:: Evidence in the guinea pig that this reaction is carried out by 3α-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 testosterone. Therefore, we set: out to isolate and clone the enzyme that performs this reaction. Testosterone sulfotransferase (TST) was isolated from the guinea Dig adrenal by using the standard procedures of ion exchange, affinity, and high-performance liquid chromatography. When purified, TST was examined by liquid-phase nondenaturing isoelectric focusing, it was found that 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 finding was further investigated by overexpressing the cDNAs for 3 alpha HST and 3 beta HST in Escherichia coli and examining the expressed proteins for TST activity. This experiment confirmed that 3 alpha HST does indeed function as a TST. In addition, 3 alpha HST was also found to sulfonate estradiol but not estrone, a finding that further suggested that 3 alpha HST may function as a general 17 beta-hydroxysteroid sulfotransferase. Published by Elsevier Science Inc.