High affinity receptor for activated thrombin coupled to G proteins that stimulate phosphoinositide hydrolysis. The cleaved signal peptide may not be degraded and may function as an intracellular angiogenesis inhibitor peptide known as parstatin. Proteolytic cleavage by thrombin generates a new N-terminus that functions as a tethered ligand. Also proteolytically cleaved by cathepsin CTSG. Cleavage at 41-Arg-|-Ser-42 by CTSG results in receptor activation while cleavage at 55-Phe-|-Trp-56 results in inhibition of receptor activation. Phosphorylated in the C-terminal tail; probably mediating desensitization prior to the uncoupling and internalization of the receptor. Belongs to the G-protein coupled receptor 1 family.