Structure and expression of the murine thromboxane A2 receptor gene

The gene encoding the murine thromboxane A2 receptor (TP) is split into three exons and spans 6.2 kilobase pairs. Primer extension analysis revealed two transcription initiation sites located approximately 210 nucleotides 5' of the first intron. The 1.2-kb 5'-flanking region lacks typical TATA and CAAT boxes but contains several potential regulatory elements including binding sites for Sp-1, NF-kappaB, AP-2, and a glucocorticoid response element. A 192-bp murine repetitive B2 element is located in the 5'-flanking region, but did not exert a negative effect on the basal promoter activity in transient transfection experiments with reporter constructs. Ribonuclease protection assays showed expression of TP RNA in several organs including thymus, spleen, kidney, and lung. In the thymus, in situ hybridization revealed transcripts in the cortex, but not in the medulla, suggesting that thromboxane A2 may play a role in the development of T-lymphocytes.