Thromboxane A(2) (TXA(2)) receptor subtypes were examined with respect to mRNA and protein levels in 1321N1 human astrocytoma cells. Specific primers were synthesized for human placental and endothelial thromboxane A(2) (TXA(2)) receptors. Reverse transcribed-poly merase chain reaction (PCR) (RT-PCR) using the specific primers amplified both human placental and endothelial TXA(2) receptor mRNAs in the cells. Anti-TXA(2) receptor antibody was raised in rabbits against a peptide sequence common to both TXA(2) receptors. The TXA(2) receptor proteins in the cells were partially purified by immunoaffinity chromatography with the anti-TXA(2) receptor antibody. The antibody recognized two proteins of 58 kDa and 55 kDa in the immunoaffinity-purified fraction. This fraction also contained G alpha(q/11) and G alpha(12). These results suggest that human astrocytoma cells express placental and endothelial TXA(2) receptor subtypes which may couple with G(q/11) and G(12).