So it contains the antigen binding site. The constant region of our T cell receptor on the gamma delta T cell basically does not change too much when we go from one cell to a different cell. And this is the portion of our T cell receptor that actually binds onto the cell membrane of the gamma delta T cell. So we know that alpha beta T cells only bind to those antigens found on either the class one and class two major histocompatibility complex on these antigen presenting cells. But what about the gamma delta T cells? What types of antigens can these gamma delta receptors actually bind to?