Binding of a C3b molecule to the C4bC2b complex (C4b2b3b) results in the formation of a C5 convertase, which cleaves C5 into C5a and C5b. C5b associates with C6, C7, C8, and C9, all …

Complement Component C3b is a serum protein that plays a crucial role in innate and adaptive immunity by binding covalently to pathogens, acting as an opsonin to target them for …

Jan 14, 2025 · C3b opsonization enhances the immune system’s ability to identify and eliminate pathogens. This process begins when C3b, a fragment of the complement protein C3, binds to …

The molecules of C3b that bind the C3 convertase itself initiate the late events, binding C5 to make it susceptible to cleavage by C2b or Bb. The larger C5b fragment triggers the assembly …

The binding of various ligands to either C3b alone (left panels) or C3b that had been presaturated with Efb-C and therefore trapped in the open state (right panels) was assessed by surface …

Oct 15, 2006 · Both decay acceleration and factor I cofactor activities involve the specific binding of regulatory proteins to C3b, with a strong dependence on ionic strength.

Oct 15, 2006 · Central to the complement system is the activated form of C3, called C3b, which attaches covalently to target surfaces 3 to amplify complement response, label cells for …

Although C3a binds to the anaphylatoxin receptor C3aR, C3b and its degradation products iC3b and C3dg interact with a variety of complement receptors (CR) to mediate immune adhesion, …

C3b is a highly unstable molecule that has a unique thioester that allows covalent binding to a microbial cell. Some C3b fragments bind to the target cell, where they act as opsonins. In the …

Jul 3, 2017 · We present a crystal structure of C3b in complex with FI and regulator factor H (FH; domains 1–4 with 19–20). FI binds C3b–FH between FH domains 2 and 3 and a reoriented …