Heterogeneous Zonal Distribution of Sulfotransferase Isoenzymes in Rat Liver

By employing dual-digitonin-pulse perfusion technique, the cytosolic fractions were prepared from periportal (PP) and perivenous (PV) hepatocytes of male and female rat livers. Sulfotransferase (ST) activities toward 2-naphthol (2NAP) (at pH 5.5 and 7.4), 4-nitrophenol, dehydroepiandrosterone (DHEA), and cortisol were measured in each fraction. DHEA-ST activity was mainly localized in PP fraction in males, while in females it was slightly higher in PP fraction than in PV samples. In contrast, phenol ST activities were higher in PV fraction in both sexes. With anti-HS-ST and anti-P-ST antisera, the levels of immunoreactive ST polypeptides were compatible with the levels of ST activities except that in female PP fraction the level of immunoreactive P-ST polypeptide was low in spite of comparatively high levels of P-ST activities. Chromatofocusing of PP and PV fractions separated P-ST activities into three major fractions (I–III), which have distinct catalytic and electrochemical properties. Fraction I was localized only in the PP samples in both sexes and revealed ST activities toward 2NAP at pH 5.5 and 7.4, while fraction II was localized in the PP and PV samples in both sexes with 2NAP-ST activity only at pH 7.4. Fraction III which had ST activities at pH 5.5 and 7.4 was present only in the PV samples in female rats, whereas in male rats it was present in both PP and PV samples. With anti-P-ST antiserum, the immunoreactive polypeptide was present in fraction III, but no immunoreactive band was detected in fractions I and II, suggesting the presence of immunochemically and electrochemically different P-ST(s) in these fractions.