If you are here, you probably understand a thing or two about antibodies. Lets do a quick review anyway.
from IPython.display import Image Image('./Media/antibody/antibody_structure_overview.png',width='1000')
Here is the full IgG that has two Fabs or antibody fragments. Each Fab has a variable (Fv) and constant (Fc) region. In Rosetta, we are mostly concerned with Fv - where the binding region actually resides. The molecule that an antibody binds to is called an antigen.