1. Describe the structure of an MHC I molecule, identifying the different polypeptide chains and domains.
2. Which domains or parts of domains participate in the following: antigen binding; binding the T-cell receptor.
3. Which domains are the most polymorphic?
the complete MHC I molecule is a heterodimer made up of one alpha chain and a smaller chain called Beta2 microglobulin. The alpha chain consists of 3 extracellular domains (alpha1,2,3), a transmembrane region and a cytoplasmic region. The polymorphic class I molecules are HLA-A, HLA-B, and HLA-C. The antigen binding site is encoded by the alpha1 and alpha2 domains. The alpha3 domains binds the coreceptor of CD8.