@article{oai:niigata-u.repo.nii.ac.jp:00016949,
 author = {布施, 一郎},
 issue = {11},
 journal = {新潟医学会雑誌, 新潟医学会雑誌},
 month = {Nov},
 note = {A patient with a mild bleeding disorder whose platelets responded defectively to thromboxane A_2 (TXA_2) was identified, and the mechanism of this dysfunction was analyzed. The platelets were defective in aggregation and release reaction in response to synthetic TXA_2 mimetic (STA_2). When the platelet TXA_2 receptor was examined with both a [^<125>I]-labeled derivative of a TXA_2 receptor antagonist ([^<125>I]-PTAOH) and [＾3H]-labeled TXA_2 agonist ([^3H]U-46619), the equilibrium dissociation rate constants(Kd)and the maximal concentrations of binding sites (Bmax) of the platelets to both ligands were within normal ranges, suggesting that the binding capacity of their TXA_2 receptor was normal. STA_2 could not induce IP3 formation and intracellular Ca^<2+> mobilization, whereas these responses to thrombin were within normal ranges. GTP ase activity was also decreased when the patient's platelet membrane was challenged with STA_2. Furthermore, we identified a single amino acid substitution (Arg^<60>→Leu) in the first cytoplasmic loop of the patient's platelet TXA_2 receptor. The mutant receptor expressed in Chinese hamster ovary cells showed decreased TXA_2-induced second messenger formation despite its normal ligand binding affinities. These results suggest that the Arg^<60> to Leu mutation is responsible for the disorder and that this region could also comprise an important functional element for interaction with G protein linked to PLC.},
 pages = {676--682},
 title = {トロンボキサンA_2による血小板活性化機構 : トロンボキサン不応症における解析から},
 volume = {111},
 year = {1997}
}