MOLECULAR-CLONING OF A POTENTIAL PROTEINASE ACTIVATED RECEPTOR

A DNA sequence encoding a G-protein-coupled receptor was isolated from a mouse genomic library. The predicted protein is similar in structur e to the thrombin receptor and has a similar activation mechanism. Whe n expressed in Xenopus laevis oocytes, the receptor was activated by l ow concentrations of trypsin (EC 3.4.21.4) and by a peptide (SLIGRL) d erived from the receptor sequence, but was not activated by thrombin ( EC 3.4.21.5). Trypsin failed to activate a mutant receptor in which th e presumed cleavage site Arg-34-Ser-35 was changed to an Arg-Pro seque nce. The agonist peptide (SLIGRL) activated equally well mutant and wi ld-type receptors. Northern blot analysis demonstrated receptor transc ripts in highly vascularized tissues such as kidney, small intestine, and stomach. Because this, to our knowledge, is the second example, be sides the thrombin receptor, of a proteolytically activated seven-tran smembrane G-protein coupled receptor, we have provisionally named it p roteinase activated receptor 2.