Molecular receptors of the Immune system. It binds to Antigens and then directs immune response (macrophages, etc.) against the antigen.
Antibodies can recognize many things, and have high specificity.
Structure
CDRs are the loops that form the binding site.
Epitope: the part of an antigen molecule to which an antibody attaches itself.
Can have different specifities on the two arms of an antibody (bispecifics)
paratope: also called an antigen-binding site, is a part of an antibody which recognizes and binds to an antigen
Gene recombination/rearrangement (V(D)J recombination)
Gene recombination through Gene splicing and other Gene expression mechanisms, and is used to create the whole diversity of antibodies.
[vid[https://www.youtube.com/watch?v=Wk2aZW-GYgM]] – [vid2|https://www.youtube.com/watch?v=h9mqsllg1Cs]]
Darwinian adaptation
Antibodies take part in the directed evolution in the immune system (which makes it a rather intelligent system).
Somatic hypermutation in the variable region