biostudies-literatureUnknown133(3)Zhao ZSecreted platelet protein disulfide isomerases, PDI, ERp57, ERp5, and ERp72, have important roles as positive regulators of platelet function and thrombosis. Thioredoxin-related transmembrane protein 1 (TMX1) was the first described transmembrane member of the protein disulfide isomerase family of enzymes. Using a specific antibody, the recombinant extracellular domain of TMX1 (rTMX1) protein, a knockout mouse model, and a thiol-labeling approach, we examined the role of TMX1 in platelet function and thrombosis. Expression of TMX1 on the platelet surface increased with thrombin stimulation. The anti-TMX1 antibody increased platelet aggregation induced by convulxin and thrombin, as well as potentiated platelet ATP release. In contrast, rTMX1 inhibited platelet aggregation and ATP release. TBlood246-251https://www.ebi.ac.uk/biostudies/studies/S-EPMC6337875biostudies-literatureThe transmembrane protein disulfide isomerase TMX1 negatively regulates platelet responses.PMC6337875Chen FEssex DWYang AZhao ZWu YZhou JfalseThe transmembrane protein disulfide isomerase TMX1 negatively regulates platelet responses.Secreted platelet protein disulfide isomerases, PDI, ERp57, ERp5, and ERp72, have important roles as positive regulators of platelet function and thrombosis. Thioredoxin-related transmembrane protein 1 (TMX1) was the first described transmembrane member of the protein disulfide isomerase family of enzymes. Using a specific antibody, the recombinant extracellular domain of TMX1 (rTMX1) protein, a knockout mouse model, and a thiol-labeling approach, we examined the role of TMX1 in platelet function and thrombosis. Expression of TMX1 on the platelet surface increased with thrombin stimulation. The anti-TMX1 antibody increased platelet aggregation induced by convulxin and thrombin, as well as potentiated platelet ATP release. In contrast, rTMX1 inhibited platelet aggregation and ATP release. T2019-01-01T00:00:00Z2019 Jan2025-04-21T15:08:39.82Z2025-04-21T15:08:39.82ZS-EPMC63378753042504910.1182/blood-2018-04-844480