Authors
Abdul Ajees Abdul Salam, K. Gunasekaran, John E. Volanakis, S.V.L. Narayana, Girish J. Kotwal, and H.M. Krishna Murthy
Summary
The human complement system is an important component of innate immunity. Complement-derived products mediate functions contributing to pathogen killing and elimination. However, inappropriate activation of the system contributes to pathogenesis of immunologic and inflammatory diseases. Complement-component 3 (C3) occupies a central position because of the manifold biologic activities of its activation fragments, including the major fragment, C3b, which anchors assembly of convertases effecting C3 and C5 activation. C3 is activated to C3b by proteolysis of its anaphylatoxin domain (ANA), by either of two C3-convertases, activating a relatively stable thioester bond, leading to covalent attachment of C3b to cell-or protein-surface hydroxyl groups through trans-esterification. Cleavage/activation of C3 exposes binding sites for factors B, H, and I, properdin (P), decay accelerating factor (DAF, CD55), membrane cofactor protein (MCP, CD46), complement receptor 1 (CR1, CD35), and viral molecules such as vaccinia-virus complement-control protein (VCP)4. C3b associates with these molecules in different configurations forming complexes, mediating activation, amplification and regulation of the complement response. Here, we present the purification and crystallization steps for C3b.Further details
The protocol was published on Protocol Exchange in 2006. To see the entire protocol, click on the source link.Advertisement
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