Protease-activated receptor PAR4 (ZCHEMR2)
The present invention relates to polynucleotide and polypeptide molecules for PAR4, a novel member of the protease-activated receptor family. The polypeptides, and polynucleotides encoding them, mediate biological responses and/or cellular signaling in response to proteases. Protease cleavage of PAR4 exposes a PAR4 extracellular amino terminal portion that serves as a ligand for the PAR4 receptor. PAR4 may be used as a target in drug screening, and further used to identify proteinaceous or non-proteinaceous PAR4 agonists and antagonists. The present invention also includes antibodies to the PAR4 polypeptides.
1. An isolated polypeptide, wherein the polypeptide comprises an amino acid sequence that is 95% or more identical to the amino acid sequence of SEQ ID NO:2 and wherein the isolated polypeptide comprises an extracellular domain that is susceptible to thrombin cleavage and when the polypeptide is expressed in COS cells, the hexapeptide GYPGQV (SEQ ID NO:7) stimulates cell division.