A novel receptor for platelet-activating factor (PAF) has been identified and shown to be highly enriched in the cerebral cortex. PAF is known to play a role in neuronal development, long-term potentiation, and brain injury, in addition to its role as a potent mediator of inflammation in the periphery. Characterization and molecular cloning of the cytosolic receptor will shed insight on how the many effects of PAF are mediated. In this proposal we describe experiments directed towards characterization and purification of this protein which will enable us to molecularly clone the gene for this novel receptor.