Interactions of Antibodies with Protein A, Protein G and Protein L
FC-Receptor binding:
1FRT.pdb
1I1A.pdb |
Protein G interaction:
1FCC.pdb
1IGC.pdb
1QKZ.pdb |
Protein A interaction:
1FC2.pdb
1DEE.pdb |
Protein L interaction:
1HEZ.pdb |
|
One way for the infecting microorganisms to evade the hostile environment in the host is to camouflage the cell surface by specific binding of different soluble plasma proteins to the cell wall. Many Gram-positive, pathogenic bacteria express cell surface proteins which are able to bind to immunoglobulins. Two of the first such proteins to be recognised were protein A, a cell wall component of Staphylococcus aureus and protein G, a protein associated with the cell wall from certain Streptococci. Both proteins have a high affinity for the interface between the CH2-CH3 domains of Fc of IgG, where they block the binding to the FC receptor. Additional binding sites in certain VH (Protein A) and CH (Protein G) domains explain their crossreactivity with some Fab and Fv fragments. Protein L, expressed at the surface of approximately 10% of Peptrostreptococcus magnus isolates binds to the variable domain of the kappa light chain of any class of immunoglobulin, without affecting the antigen - antibody interaction
Binding specificities of recombinant Protein A, Protein G and Protein L immunoglobulin binding domains |
