Reconstitution of recombinant N-formyl chemotactic peptide receptor with G protein

A recombinant human neutrophil N-formyl peptide receptor (rFPR) expressed in transfected mouse fibroblasts (TX2 cells) was analyzed for its ability to couple physically with the heterotrimeric G protein, Gi. Immunoprecipitation of photoaffinity-labeled rFPR and endogenous neutrophil formyl peptide receptor (nFPR) with an anti-FPR peptide antibody demonstrated that the receptors were identical in both size and extent of glycosylation. Coupling of rFPR with endogenous TX2 Gi was demonstrated by coimmunoprecipitation of the two proteins with an anti-Gi antibody. Moreover, rFPR was able to form a physical complex with purified Gi in a soluble reconstitution system. We observed similar affinities of rFPR and nFPR for Gi. This report provides the first direct evidence that rFPR associates physically with Gi and provides a foundation for analysis of the G protein coupling capacity of mutant rFPRs.