Steve Ealick's Research Group

Human Desarg-C5A

PDB file:




In the classical activation of the complement protein pathway, the formation of immune complexes triggers a cascade of proteolytic cleavages of complement proteins. The activation of complement component C5 by C5 convertase initiates the assembly of the late complement components, C5b–C9, into the membrane-attack complex. C5a is an anaphylatoxin that is derived from the cleavage of C5. This 74-amino-acid glycoprotein is a potent chemotactic factor for all cells of the myeloid lineage, including neutrophils, eosinophils, basophils and mast cells, causing numerous cellular responses such as chemotaxis, aggregation and adhesion


Each crystal form contained an asymmetrical dimer in the asymmetric unit. The crystal structure shows a three-helix central core in each monomer connected by short loops
located at the surface of the dimer.

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The residues deemed important for binding to the C5a receptor are shown at right.


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Cook WJ, Galakatos N, Boyar WC, Walter RL, Ealick SE. Crystal Structure of Human Desarg-C5A. Acta Crystallogr. D 66:190-197 (2010).

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