Antibodies

Antibodies are part of the body’s defense against foreign invaders. They are proteins produced by a type of white blood cell, called B cells, and like any proteins, their structure determines their function. Antibodies have a variable region that is different for each antibody that binds to a different antigen. An antigen is anything that the body does not recognize as “self” and can range from pieces of virus capsids to pieces of bacterial surface proteins. The antibody is structured in a “Y” shape and has light and heavy chains that are held together by disulfide bonds. The top of the “Y” is where there is a variable antigen binding region. The constant region of the antibody allows for consistency of response and the variable top allows for different identification of foreign bodies. The antibody gene allows for the randomization of the antigen binding amino acid structure which is what creates the variability in the region. The randomized antibody gene is created by V(D)J recombination. It is non-template directed and done by tdt polymerase which is a form of DNA polymerase.