2A73:
reference: Structures of complement component C3 provide insights into the function and evolution of immunity., Janssen BJ, Huizinga EG, Raaijmakers HC, Roos A, Daha MR, Nilsson-Ekdahl K, Nilsson B, Gros P, Nature. 2005 Sep 22;437(7058):505-11. PMID: 16177781

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