Specificity of the thrombin receptor for agonist peptide is defined by its extracellular surface

Study of human and Xenopus thrombin receptor homologs reveals that thrombin receptor activation requires agonist interaction with the extracellular domain. Altering the xenopus receptor aminoterminal exodomain and loops with human counterparts changes the receptor specificity to human type. The extracellular surface determines thrombin receptor specificity.