Immunoglobulins are heterodimeric proteins composed of 2 heavy and 2 light chains. They
can be separated functionally into variable domains that bind antigens and constant
domains that specify effector functions, such as activation of complement or binding to Fc
receptors. The variable domains are created by means of a complex series of gene
rearrangement events and can then be subjected to somatic hypermutation after exposure to
antigen to allow affinity maturation. Each variable domain can be split into 3 regions of …