Structure of a<unk>  with light and heavy chains. The<unk>  region <unk>  region) is a region on an antibody that binds to<unk> s. It is composed of one constant and one variable domain of each of the heavy and the light chain. The variable domain contains the paratope (the<unk><unk>  site), comprising a set of complementarity-determining regions, at the amino terminal end of the monomer. Each arm of the Y thus binds an epitope on the<unk> .
Fragment antigen-binding
Alloantigen recognition
Antigen presentation
Antibody opsonization
Complement-dependent cytotoxicity
Receptor editing
Oocyte selection
Autoimmune regulator