Occurrence of estrone, estradiol, and testosterone glucuronyltransferase activities was tested in a well-differentiated hepatoma, Reuber H-35. Transferase activities for estrone and estradiol were found in the hepatoma. The Michaelis-Menten kinetics of these two microsomal glucuronyltransferase activities were similar in hepatoma and in liver preparations, except for a somewhat higher apparent Km for estradiol in the hepatoma preparations. Under the same experimental conditions, only trace amounts of testosterone glucuronyltransferase activity could be detected in the hepatoma preparations. By contrast, in liver microsomal preparations, testosterone glucuronyltransferase activity was the highest among the steroid glucuronyltransferase activities tested.

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This work was supported by Grants CA-14729 and CA-13038 from the National Cancer Institute, USPHS.

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