The protease-activated receptor 1 possesses a functional and cleavable signal peptide which is necessary for receptor expression.

The protease-activated receptor 1 (PAR1) is activated by thrombin cleavage releasing the physiologically-relevant parstatin peptide (residues 1-41). However, the actual length of parstatin was unclear since the receptor may also possess a cleavable signal peptide (residues 1-21) according to prediction programs. Here, we show that this putative signal peptide is indeed functional and removed from the PAR1 resolving the question of parstatin length.