So the gamma delta T cells contain T cell receptors that are slightly different. Instead of having an alpha and a basic polypeptide submune we have a gamma and a delta polypeptide subune as shown in the following diagram. So the purple is our gamma and the blue is our delta. Now, we have a variable portion on our T cell receptor, the protein. And this basically varies from one cell to a different cell. And that's because this is the portion of the T cell receptor that contains that specific sequence of amino acids that can bind to some particular antigen.