The Antibody Surface Involved in Antigen Binding Varies Depending on the Size

The antibody surface involved in antigen binding varies depending on the size and nature of the antigen. This surface can be concave or flat, and sometimes, can have extended protrusions. This is accomplished by:

A) Flexibility in the hinge regions of the antibody allowing rotation of the antigen-binding sites
B) Some antibodies using V region framework sequences instead of the CDRs to bind antigen
C) The ability of different CDR sequences to form many structurally distinct shapes and surfaces
D) The ability of the same heavy chain to pair with different light chains
E) The differential usage of κ versus λ light chains, as κ chains form concave binding sites whereas λ chains make flatter surfaces