Fig. 2

Proteolytic PAR cleavage. a N-terminal sequences of human PARs (PAR1–4) containing potential cleavage sites. b Proteolytic cleavage of PARs by soluble exogenous proteases exposes new N-terminal sequences that serve as tethered ligands for G protein dependent activation of receptors. Alternatively, proteolytic cleavage at other sites destroys the function of the receptor to prevent intracellular signal transduction