PAR1 receptor bound to anti-platelet drug, molecular model. Human protease-activated receptor 1 (PAR1, white-pink, upper left) bound in a cell membrane with the antagonist drug vorapaxar (centre right and lower right), with the complex being acted on by thrombin serine protease (pink). Protease-activated receptor 1 (PAR1) is the prototypical member of a family of G-protein-coupled receptors that mediate cellular responses to thrombin and related proteases. PAR1 is a key part of re-myelination and neuron repair processes. Drugs that affect it are being studied for use in diseases such as multiple sclerosis, as well as their use to inhibit coagulation (anti-platelet drugs).