Publications

• Characterization of human liver thermostable phenol sulfotransferase (SULT1A1) allozymes with 3,3',5-triiodothyronine as the substrate.

  Li X., Clemens D.L., Cole J.R., Anderson R.J.

  Sulfotransferase 1A1 (SULT1A1) (thermostable phenol sulfotransferase, TS PST1, P-PST) is important in the metabolism of thyroid hormones. SULT1A1 isolated from human platelets displays wide individual variations not only in the levels of activity, but also in thermal stability. The activity of the ... >> More

  Sulfotransferase 1A1 (SULT1A1) (thermostable phenol sulfotransferase, TS PST1, P-PST) is important in the metabolism of thyroid hormones. SULT1A1 isolated from human platelets displays wide individual variations not only in the levels of activity, but also in thermal stability. The activity of the allelic variant or allozyme SULT1A1*1, which possesses an arginine at amino acid position 213 (Arg213) has been shown to be more thermostable than the activity of the SULT1A1*2 allozyme which possesses a histidine at this position (His213) when using p-nitrophenol as the substrate. We isolated a SULT1A1*1 cDNA from a human liver cDNA library and expressed both SULT1A1*1 and SULT1A1*2 in eukaryotic cells. The allozymes were assayed using iodothyronines as the substrates and their biochemical properties were compared. SULT1A1*1 activity was more thermostable and more sensitive to NaCl than was SULT1A1*2 activity when assayed with 3,5,3'-triiodothyronine (T(3)). Sensitivities to 2,6-dichloro-4-nitrophenol (DCNP) and apparent K(m) values for SULT1A1*1 and for SULT1A1*2 with iodothyronines were similar. Based on K(m) values, the preferences of these SULT1A1 allozymes for iodothyronine substrates were the same (3,3'-diiodothyronine (3,3'-T(2))>3', 5',3-triiodothyronine (rT(3))>T(3)>thyroxine (T(4))>>3,5-diiodothyronine (3,5-T(2))). SULT1A1*1 activity was significantly higher than the SULT1A1*2 activity with T(3) as the substrate. Potential differences in thyroid hormone sulfation between individuals with predominant SULT1A1*1 versus SULT1A1*2 allozymes are most likely due to differences in catalytic activity rather than substrate specificity. << Less

  J Endocrinol 171:525-532(2001) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Expression and characterization of a novel thyroid hormone-sulfating form of cytosolic sulfotransferase from human liver.

  Wang J., Falany J.L., Falany C.N.

  Sulfation is an important conjugation reaction for a wide range of endogenous and exogenous compounds in humans, including steroids, bile acids, catecholamine neurotransmitters and thyroid hormones. The cDNA for a distinct human cytosolic sulfotransferase (ST), hST1B2, has been isolated from a hum ... >> More

  Sulfation is an important conjugation reaction for a wide range of endogenous and exogenous compounds in humans, including steroids, bile acids, catecholamine neurotransmitters and thyroid hormones. The cDNA for a distinct human cytosolic sulfotransferase (ST), hST1B2, has been isolated from a human liver lambdaZap cDNA library. The hST1B2 cDNA consists of 1144 bp and contains the coding region for a novel human cytosolic ST that has been termed hST1B2 on the basis of its sequence similarity to a rat sulfotransferase, ST1B1. The hST1B2 cDNA contains an 888-bp open reading frame that encodes a 296-amino acid protein with a calculated molecular mass of 34,897 Da. The hST1B2 cDNA also has a 127-bp 5' untranslated region (UTR) and a 129-bp 3'-UTR, including a 22-bp poly(A)+ tract. The amino acid sequence of hST1B2 is 74%, 53%, 53%, 52%, 56%, and 34% identical to the amino acid sequences of rat ST1B1 and human P-PST-1, P-PST-2, M-PST, EST, and DHEA-ST, respectively. Enzymatically active hST1B2 was expressed in the bacterial expression vector pKK233-2 for kinetic characterization and in the bacterial expression vector pQE-31, which generates a histidine-tagged fusion protein for the generation of antibodies. Expressed hST1B2 sulfates small phenols such as 1-naphthol and p-nitrophenol and thyroid hormones, including 3,3'-diiodothyronine, triiodothyronine, reverse triiodothyronine, and thyroxine. No activity was detected when several steroids or dopamine were tested as substrates. High levels of hST1B2 message were detected by Northern blot analysis in RNA isolated from human liver, colon, small intestine, and blood leukocytes. Immunoblot analysis detected a protein with the same mass as expressed hST1B2 in several human tissues that also possessed hST1B2 message. These results indicate that a novel cytosolic ST is present in human tissues, which may have an important role in thyroid hormone and xenobiotic metabolism. << Less

  Mol. Pharmacol. 53:274-282(1998) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Characterization of thyroid hormone sulfotransferases.

  Visser T.J., Kaptein E., Glatt H., Bartsch I., Hagen M., Coughtrie M.W.

  Sulfation is an intriguing pathway of thyroid hormone metabolism since it facilitates the degradation of the hormone by the type I deiodinase (D1). This study reports the preliminary characterization of iodothyronine sulfotransferase activities of rat and human liver cytosol and recombinant rSULT1 ... >> More

  Sulfation is an intriguing pathway of thyroid hormone metabolism since it facilitates the degradation of the hormone by the type I deiodinase (D1). This study reports the preliminary characterization of iodothyronine sulfotransferase activities of rat and human liver cytosol and recombinant rSULT1C1 and hSULT1A1 isoenzymes. All these enzyme preparations catalyzed the sulfation of--in decreasing order of efficiency--3,3'-diiodothyronine (3,3'-T2) > 3,3',5-triiodothyronine (T3) approximately 3,3',5'-triiodothyronine (rT3) > thyroxine (T4). 3,3'-T2 sulfotransferase activity was found to be higher in male than in female rat liver, which has also been shown by others for the expression of rSULT1A1 and rSULT1C1. No sulfation of iodothyronines was observed with rSULT1A1. Different phenol derivatives were found to be potent inhibitors of the sulfation of 3,3'-T2 by native and recombinant sulfotransferases, with pentachlorophenol and 2,4,6-tribromophenol being the most potent. The inhibitions exerted by the different phenols on 3,3'-T2 sulfation by rSULT1C1 correlated better with the effects observed in male than with those in female liver. A strong correlation was also observed between the inhibition profiles of human liver cytosol and hSUL1T1A1. These results suggest that: (1) rSULT1C1 is an important isoenzyme for the sulfation of thyroid hormone in male rat liver; (2) another isoenzyme with similar properties, perhaps rSULT1B1, is responsible for thyroid hormone sulfation in female rat liver and may also contribute to this process in male rat liver; and (3) hSULT1A1 is an important isoenzyme for thyroid hormone sulfation in human liver. << Less

  Chem Biol Interact 109:279-291(1998) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.