C5a is one of the most potent inflammatory peptides generated by complement activation. This peptide has many functions such as acting as a chemoattractant for neutrophils. C5a acts as a vasodilator and activates the coagulation pathway just to name a few.C5a exerts its numerous actions by binding to C5aR and C5L2. C5aR belongs to the superfamily of G-protein coupled receptors (GPCRs). Like all members, C5aR has seven transmembrane domains, an extracellular N-terminus and an intracellular C-terminal tail. C5aR can form homodimers or heteromer with CCR5, chemokine receptor, for example8,9. Activation of C5aR by C5a binding causes Ca2+ mobilization.C5aR expression is detected in neutrophils, eisinophils, basophils and monocytes. The receptor is also expressed in lung and liver.Blocking C5aR by peptides or organic small molecules is in the pipeline for treating chronic inflammatory disorders/diseases like arthritis, inflammatory bowel disease and lung/liver injuries.
