Thursday, April 3, 2014
Bird's-eye view of IgG hexamers.
The complement component 1 q
subcomponent (C1q) complex has six
antibody-binding headpieces (blue circles) and activates the
recruit and activate C1q, but individual IgG antibody molecules bind the
complex with weak affinity.
As reported by Diebolder et al., monoclonal IgGs
can be engineered with point mutations that enhance their ability to assemble
into hexamers after binding to a target antigen on the cell surface.
This IgG hexamer structure
is better able to recruit and activate the C1q complex, leading to increased
complement activation and more potent complement-dependent cytotoxicity against
the target cell compared with individual IgG molecules.