Abstract: Objective To investigate the physical association between G protein-coupled receptors (GPCR) including C5a receptor (C5aR), C5a Like Receptor 2 (C5L2) and chemotaxis inhibitory protein (CHIPs) secreted by Staphylococcus aureus. Methods The purified CHIPs was incubated with HEK 293T cells overexpressing C5aR, C5L2 and C-X-C chemokine receptor type 3 (CXCR3). Binding signal was detected by Western-blotting. Results HEK 293T cells overexpressing C5aR can efficiently bind to CHIPs. No apparent association between CHIPs and C5L2 or CXCR3 was detected. Conclusion C5aR not C5L2 is a membrane receptor for binding CHIPs, It suggesting a difference between C5aR and C5L2 in association with binding CHIPs.

Key words: CHIPs, C5aR, C5L2, the relationship of the structures