Dehydroepiandrosterone sulphotransferase (DHEA-ST) catalyses the 3'-phosphoadenosine 5'-phosphosulphate-dependent sulphation of a wide variety of steroids in human liver and adrenal tissue and is responsible for most, if not all, of the sulphation of bile acids in human liver. This report describes the isolation, characterization and expression of a cDNA which encodes human liver DHEA-ST. The DHEA-ST cDNA, designated DHEA-ST8, was isolated from a Uni-Zap XR human liver cDNA library and is composed of 1060 bp and contains an open reading frame encoding a 285-amino-acid protein with a molecular mass of approx. 33765 Da. Translation of DHEA-ST8 in vitro generated a protein identical in molecular size with that of DHEA-ST. Expression of DHEA-ST8 in COS-7 cells produces an active DHEA-ST protein which is capable of sulphating DHEA, has the same molecular mass as human liver DHEA-ST and is recognized by rabbit anti-(human liver DHEA-ST) antibodies. Northern-blot analysis of human liver RNA detects the presence of three different size transcripts; however, Southern-blot analysis of human DNA suggests that only one gene may be present in the genome. These results describe the cloning of a human ST which has an important role in the sulphation of steroids and bile acids in human liver and adrenals.

Human tissues possess at least four distinct forms of cytosolic ST, three of which are involved in the sulfation of steroids. DHEA-ST is responsible for the majority of hydroxysteroid and bile acid sulfation in human tissues and abundant levels of the enzyme are present in human liver and adrenal tissues. In the adult human adrenal, DHEA-ST has been localized immunologically to the zona reticularis of the adrenal cortex. No age- or gender-related differences in the expression of DHEA-ST activity in adult human liver cytosols have been reported. The cDNA encoding DHEA-ST has been isolated from a human liver cDNA library and expressed in both mammalian COS cells and E. coli. Purification and molecular characterization studies suggest a single form of DHEA-ST in human tissues. The properties of DHEA-ST expressed in either mammalian or bacterial cells are very similar to those of the native enzyme. DHEA-ST can also bioactivate a number of procarcinogens to reactive electrophilic forms. Hydroxymethyl PAHs are sulfated and bioactivated at a relatively rapid rate by DHEA-ST, whereas 1'-hydroxysafrole and N-hydroxy-2-acetylaminofluorene are bioactivated to a lesser extent.

The primary structures of the alpha chains in hemoglobins from three stocks of mice with the Hbaw2, Hbaw3, and Hbaw4 haplotypes were determined to establish whether the tentative alpha-chain assignments based on the results of isoelectric focusing patterns were correct. These Hba haplotypes were identified in laboratory descendants of feral mice captured in different parts of the world. Hemoglobin from "Centreville", Maryland, Mus musculus domesticus (Hbaw2) contains equal amounts of alpha chains 1 and 3. Hemoglobin from "Czech" Mus musculus musculus (Hbaw4) contains equal amounts of alpha chains 3 and 4. Amino acid analysis of the alpha-globins of "Skive" Danish Mus musculus musculus (Hbaw3) establishes that its hemoglobin is comprised of about one-third alpha chain 2 as expected plus a greater amount of a unique alpha chain that has not been described previously. This unique alpha chain has glycine at position 25, isoleucine at position 62, and serine at position 68; it is called chain 7. It may represent an intermediate in the evolution of genes that code for chain 2 (which has glycine, valine, and serine at positions 25, 62, and 68, respectively) and chain 4 (which has valine, isoleucine, and serine at positions 25, 62, and 62, respectively).