'One of the major oxysterols in the human circulation is 4 beta-hydroxycholesterol formed from cholesterol by the drug-metabolizing enzyme cytochrome P450 3A4. Deuterium-labeled 4 beta-hydroxycholesterol was injected into two healthy volunteers, and the apparent half-life was found to be 64 and 60 h, respectively. We have determined earlier the half-lives ... More
Functional and molecular characterization of nucleobase transport by recombinant human and rat equilibrative nucleoside transporters 1 and 2. Chimeric constructs reveal a role for the ENT2 helix 5-6 region in nucleobase translocation.
Authors Yao Sylvia Y M; Ng Amy M L; Vickers Mark F; Sundaram Manickavasagam; Cass Carol E; Baldwin Stephen A; Young James D;
JournalJ Biol Chem
PubMed ID12006583
'The human (h) and rat (r) equilibrative (Na(+)-independent) nucleoside transporters (ENTs) hENT1, rENT1, hENT2, and rENT2 belong to a family of integral membrane proteins with 11 transmembrane domains (TMs) and are distinguished functionally by differences in sensitivity to inhibition by nitrobenzylthioinosine and coronary vasoactive drugs. Structurally, the proteins have a ... More
Mutation at the catalytic site of topoisomerase I in CEM/C2, a human leukemia cell line resistant to camptothecin.
AuthorsFujimori A, Harker WG, Kohlhagen G, Hoki Y, Pommier Y
JournalCancer Res
PubMed ID7882333
'We developed previously a resistant cell line, CEM/C2, from the human leukemia cell line CCRF-CEM by stepwise selection in camptothecin. This cell line is 974-fold more resistant to camptothecin than parental cells. Resistance is only partially explained by 2-fold reductions in topoisomerase I protein and mRNA levels. We further investigated ... More
Characterization of a novel 23-kilodalton protein of unactive progesterone receptor complexes.
AuthorsJohnson JL, Beito TG, Krco CJ, Toft DO
JournalMol Cell Biol
PubMed ID8114727
'Immunoprecipitation of unactivated avian progesterone receptor results in the copurification of hsp90, hsp70, and three additional proteins, p54, p50, and p23. p23 is also present in immunoaffinity-purified hsp90 complexes along with hsp70 and another protein, p60. Antibody and cDNA probes for p23 were prepared in an effort to elucidate the ... More
Cloning of cockroach allergen, Bla g 4, identifies ligand binding proteins (or calycins) as a cause of IgE antibody responses.
AuthorsArruda LK, Vailes LD, Hayden ML, Benjamin DC, Chapman MD
JournalJ Biol Chem
PubMed ID8537384
An allergen cloned from a Blattella germanica (German cockroach) cDNA library, encoded a 182-amino acid protein of 20,904 Da. This protein, designated B. germanica allergen 4 (Bla g 4), was expressed as a glutathione S-transferase fusion protein in Escherichia coli and purified by affinity chromatography and high-performance liquid chromatography. The ... More
Cloning of Chinese hamster DNA topoisomerase I cDNA and identification of a single point mutation responsible for camptothecin resistance.
AuthorsTanizawa A, Beitrand R, Kohlhagen G, Tabuchi A, Jenkins J, Pommier Y
JournalJ Biol Chem
PubMed ID8244980
A camptothecin-resistant (DC3F/C-10) Chinese hamster cell line that contains a catalytically altered and camptothecin (CPT)-resistant DNA topoisomerase I (top 1) (Tanizawa, A., and Pommier, Y. (1992) Cancer Res. 52, 1848-1854) and the parent cell line (DC3F) were used to compare top 1 mRNAs and cDNAs. Northern blot analysis showed a ... More
Reconstitution of enzymatic activity by the association of the cap and catalytic domains of human topoisomerase I.
AuthorsYang Z, Champoux JJ.
JournalJ Biol Chem
PubMed ID12077150
When human topoisomerase I binds DNA, two opposing lobes in the enzyme, the cap region (amino acid, residues 175-433) and the catalytic domain (Deltacap, residues 433 to the COOH terminus) clamp tightly around the DNA helix to form the precleavage complex. Although Deltacap contains all of the residues known to ... More
1-Cys peroxiredoxin overexpression protects cells against phospholipid peroxidation-mediated membrane damage.
1-Cys peroxiredoxin (1-cysPrx) is a novel antioxidant enzyme able to reduce phospholipid hydroperoxides in vitro by using glutathione as a reductant. This enzyme is widely expressed and is enriched in lungs. A fusion protein of green fluorescent protein with 1-cysPrx was stably expressed in a lung-derived cell line (NCI-H441) lacking ... More