The role of the C-terminal tail in protease-activated receptor-2-mediated Ca super(2+) signalling, proline-rich tyrosine kinase-2 activation, and mitogen- activated protein kinase activity

C-terminal truncation mutants were made to investigate the role of the C- terminus in coupling proteinase-activated receptor-2 (PAR-2) to various signalling pathways. Membrane expression of the delta 15, delta 34, delta 43, and delta 34-43 mutants was similar; however, expression of delta tail was lost, as was agonist-mediated internalisation of delta tail, delta 43, and delta 34-43. Additionally, trypsin and SLIGKV-stimulated [ super(3)H]IP accumulation was abrogated in cells transiently expressing delta 43 or delta 34-43 truncations, but remained unaffected in cells expressing delta 34 or delta 15. PAR-2 agonist-stimulated intracellular Ca super(2+) mobilisation and PYK-2 activity were also abolished by delta tail, delta 43, and delta 34-43 mutants. However, trypsin-stimulated stress-activated protein kinases (SAPKs) or extracellular signal-regulated kinase (ERK) activities were unaffected by the delta 34-43 mutation, although activity was abrogated following delta 43 or delta tail truncations, suggesting that Ca super(2+) mobilisation, PYK-2, or receptor internalisation are not requied for activation of SAPKs or ERK. These studies identify a novel sequence within the PAR-2 C-terminus essential for InsP sub(3) generation and PYK-2 activity but not mitogen-activated protein kinase (MAPK) activation.