Figure 2.

Peptidases act as biased agonists at GPCRs. (A) Trypsin cleaves PAR₂ to create a new N-terminus that activates PAR₂ mobilizing intracellular calcium and promoting phosphorylation (p) of ERK1/2. (B) Cathepsin G cleaves PAR₂, but does not elicit any known signalling and prevents activation by other peptidases such as trypsin. (C) Other peptidases such as elastase-2, cleave PAR₂ at a site distinct from trypsin. The action of this peptidase does not mobilize intracellular calcium, but does activate ERK1/2.