Characterization of the complete genomic structure of human thromboxane synthase gene and functional analysis of its promoter.
Thromboxane A2 (TXA) is a potent vasoconstrictor and mediator of platelet aggregation. Thromboxane synthase (TXAS), which catalyzes the biosynthesis of TXA, is a member of the cytochrome P450 superfamily. We report here the complete genomic structure of the human TXAS gene. The gene contains 13 exons and is 193 kb long, the largest P450 gene ever isolated. The physical localization of the TXAS gene on the genetic map of human chromosome 7 was established. A major transcription start site is located at a motif similar to the initiator element where the transcription factor TFII-I binds. We have sequenced up to 1.6 kb of the 5'-flanking region of the TXAS gene and characterized the promoter activity in a human megakaryocyte cell line and endothelial cells. Our results demonstrated that the nucleotides -248/+137 relative to the major transcription start site conferred a full promoter activity of the TXAS gene. This region was regulated negatively by cis-elements located between -1562 and -248. Moreover, the regions outside -1562/+137 might control tissue-specific TXAS expression.
Vascular Biology Research Center and Division of Hematology, Department of Internal Medicine, University of Texas-Houston Medical School, 77030, USA.
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R
Tazawa
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Green
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K
Ohashi
K K
KK
Wu
L H
LH
Wang
D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002478:Cells, Cultured; D002874:Chromosome Mapping; D002897:Chromosomes, Human, Pair 7; D003360:Cosmids; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism; D004730:Endothelium, Vascular / Q000201:enzymology; D005091:Exons; D006801:Humans; D007438:Introns; D004915:Leukemia, Erythroblastic, Acute; D008156:Luciferases / Q000096:biosynthesis; D008969:Molecular Sequence Data; D005810:Multigene Family; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis; D015183:Restriction Mapping; D013930:Thromboxane-A Synthase / Q000096:biosynthesis / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D014471:Umbilical Veins
D017931:DNA Primers; D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D003577:Cytochrome P-450 Enzyme System; D008156:Luciferases; D013930:Thromboxane-A Synthase