So an antigen presenting cell is a type of white blood cell whose function is to engulf our antigens and take those antigens and present those antigens on the membrane of those APCs. So basically, these antigen presenting cells contain these protein complexes on the membrane known as the major histocompatibility complex. And what these protein complexes do is they're capable of binding these antigens that the cells actually engulf. Now what the role of the AlphaBeta T lymphocyte is is to actually bind to these antigen MHC complexes once the antigen presenting cell actually engulfs that antigen and places it onto that MHC in the first place. Now, on top of having that T cell receptor that consists of an alpha and a beta subunit these T lymphocytes also contain glycoproteins that are necessary to actually bind to the antigen presenting cells. Now, we have two different types of glycoproteins.