Description
Human Complement 5a (C5a) is an enzymatically generated glycoprotein that belongs to a family of structurally and functionally related proteins known as anaphylatoxins. Human C5a has four alpha -helices plus three intrachain disulfide bonds that create a triple loop structure . In serum, proteolytic processing removes the C‑terminal arginine, creating a low activity C5adesArg74 molecule . Human C5a is 60% and 54% aa identical to mouse and rat C5a, respectively. C5a binds to a signaling G-protein coupled receptor (C5aR/CD88) and a nonsignaling GPCR termed C5L2 . Activation of Cd88 results in neutrophil chemotaxis and endothelial cell activation . It also triggers an oxidative burst in macrophages and neutrophils, and induces release of histamine in basophils and mast cells.