Nüsing R M, Hirata M, Kakizuka A, Eki T, Ozawa K, Narumiya S
Department of Pharmacology, Kyoto University Faculty of Medicine, Japan.
J Biol Chem. 1993 Nov 25;268(33):25253-9.
The human thromboxane A2 gene, present as a single copy, spans over 15 kilobases (kb) and contains 3 exons divided by 2 introns. The first intron, intron 1, exists in the 5'-noncoding region, 83 base pairs upstream from the ATG start site and is 6.3 kb long. Intron 2 with a length of 4.3 kb is located at the end of the sixth transmembrane region, thereby separating it from the downstream coding sequences including the seventh transmembrane region and the 3'-untranslated region. By rapid amplification of 5'-cDNA ends, transcription initiation sites starting in two different putative promoter regions were determined. In the 5'-flanking region of these transcription initiation sites, no typical TATA box exists. The major promoter, the promoter region I, contains four potential SP-1 binding sites and several potential binding sites for other transcription factors. By polymerase chain reaction analysis, a small portion of the RNA transcribed from this gene was shown to contain an additional 115-base pair long noncoding exon, exon 1b, which is located in intron 1. No additional exon in intron 2 was detectable, indicating that a single type of thromboxane A2 receptor protein is encoded by this gene. Chromosomal localization was carried out by fluorescence in situ hybridization of cloned genomic DNA to the metaphase chromosome. The gene was assigned to 19p13.3 of human chromosome.
人类血栓素A2基因以单拷贝形式存在，跨度超过15千碱基（kb），包含3个外显子，被2个内含子分隔。第一个内含子，即内含子1，存在于5'-非编码区，位于ATG起始位点上游83个碱基对处，长度为6.3 kb。长度为4.3 kb的内含子2位于第六个跨膜区域末端，从而将其与包括第七个跨膜区域和3'-非翻译区的下游编码序列分隔开。通过5'-cDNA末端的快速扩增，确定了起始于两个不同假定启动子区域的转录起始位点。在这些转录起始位点的5'-侧翼区域，不存在典型的TATA盒。主要启动子，即启动子区域I，包含四个潜在的SP-1结合位点和几个其他转录因子的潜在结合位点。通过聚合酶链反应分析，显示从该基因转录的一小部分RNA包含一个额外的115个碱基对长的非编码外显子，外显子1b，它位于内含子1中。在内含子2中未检测到额外的外显子，表明该基因编码单一类型的血栓素A2受体蛋白。通过将克隆的基因组DNA与中期染色体进行荧光原位杂交进行染色体定位。该基因被定位到人类染色体的19p13.3。
