HUMAN JEJUNAL ESTROGEN SULFOTRANSFERASE AND DEHYDROEPIANDROSTERONE SULFOTRANSFERASE - IMMUNOCHEMICAL CHARACTERIZATION OF INDIVIDUAL VARIATION

Sulfate conjugation is an important metabolic pathway for many drugs, xenobiotic compounds, and steroid hormones. Human tissues express five cytoplasmic sulfotransferase (ST) enzymes: estrogen ST (EST), dehydro epiandrosterone (DHEA) ST, and three phenol STs (PSTs), Both EST and D HEA ST can catalyze the sulfonation of steroid compounds, including ex ogenously administered steroids such as ethinyl estradiol, We set out to characterize immunochemically the nature and extent of individual v ariation in the expression of EST and DHEA ST in the human small intes tine after Northern blot analysis had demonstrated that both enzymes w ere expressed in that tissue. Polyclonal antibodies to human EST and D HEA ST were developed, and Western blot analysis demonstrated that the antibodies were specific, We then performed quantitative Western blot s of EST and DHEA ST in 62 samples of human jejunal mucosa. Large indi vidual variations in immunoreactive EST and DHEA ST protein levels wer e present in those 62 tissue samples, However, there was not a signifi cant correlation between levels of immunoreactive protein for the two enzymes (r(s) = 0.143, p = 0.262), indicating that EST and DHEA ST in the human jejunum are regulated independently. Furthermore, immunoreac tive EST and DHEA ST protein levels in these samples did not differ si gnificantly between the genders, and neither was correlated significan tly with time of tissue storage, patient age, or underlying pathology. Frequency distribution histograms of immunoreactive protein values we re skewed far both enzymes, and the DHEA ST frequency distribution see med to be bimodal, These results represent a step toward understanding the molecular basis for individual variation in the expression and fu nction of EST and DHEA ST in the human small intestine.