every B and T cell is going to have a single type of antigen receptor, and that's going to be specific. Toe a single type of Auntie Jen here you can see an example of this. We have different B cells, each with a specific type of B cell receptor that is meant for a specific type pathogen. Now, immuno globulin are going to be the class of proteins that include antibodies and B cell receptors. And there's actually five classes. You don't need to worry about knowing these names. I just throw them in there in case you're curious. And essentially, what I want you to know is that each is a type eso each, you know, subtype that you see here is gonna have ah, unique heavy chain and function. What is a heavy chain? We're gonna get to that in a second. So the B cell receptor is has the same structure is the antibodies produced by those B cells and it's gonna be made up of what were called heavy chains and light chains, two of each, actually too heavy chains to light chains. The light chain is the smaller of the poly peptides and the heavy chain is the larger, and this terminology also applies to antibodies. It's not just specific for B cell receptors. So here, looking at RB cell receptor, these little pieces that you see on either side, those are the light chains, and these bigger pieces that you see here and here will draw a red line through them just to be super crystal clear. Those bigger pieces, those oops are the heavy chains. And as I've said before, you know, the only real difference between the B cell receptor and antibodies it produces is that the B cell receptor is gonna have a trans membrane domain. Now, T cell receptors are gonna be fairly similar in structure to like one of the arms of immuno globulin. And it's going to instead of being made up of a heavy chain and a light chain gonna be made of what we call an Alfa chain and abated chain. And I'm gonna jump out of the way here and you can see that we have a T cell receptor right here T cell receptor, and it has its Alfa chain and its beta chain, and it's kind of like just one of these arms from the B cell receptor from an antibody. And here is its binding site. And here is the anchor into the membrane. And the main difference between these B cell receptors and T cell receptors on this is something we're gonna talk about more in just a moment is that B cell receptors will actually bind directly to antigens. But T cell receptors on Lee bind to antigens that are presented on the surfaces of other cells in process known very creatively as antigen presentation. So with that, let's actually flip the page.
