Questions on MHC Structure

Most of these questions can be answered by referring to the images at http://www.umass.edu/microbio/chime/mhc/index.htm. It will also be helpful to refer to the appropriate chapter of a textbook of immunology.

These questions will help you focus your tour of MHC structure. It is recommended that you print this page and write your answers. Have your answers checked by your instructor.

    MHC Class I Extracellular Domains

  1. How many polypeptide chains make up MHC class I?

  2. Which chains are invariant? Which show allelic variability?

  3. Which domains have immunoglobulin-like structure?

  4. Does CD8 bind to a domain of high or low variability? What would you predict about the variability of the amino acids which bind CD8?

  5. Which end of the molecule is anchored to the cell membrane, and which end binds to the TCR?

    Cleft of MHC Class I

  6. Which regions of MHC contact the antigenic peptide?

  7. What secondary structures make up the walls ("lips") and the floor of the cleft?

  8. Are the ends of the peptide exposed or buried?

  9. Is the backbone of the peptide nonamer straight?

  10. What kinds of bonds hold the peptide into the cleft?

  11. What kinds of bonds form between the TCR and the peptide-MHC complex?

    Viral Peptides

  12. What are the anchor residues and positions for H-2Kb?

    MHC Class II

  13. What major structural differences, if any, do you see between the four extracellular domains of class I vs. class II? What about secondary structure?

  14. How many invariant chains are present in class II?

  15. What holds the alpha and beta chains of class II together?

    Peptide in MHC Class II

  16. Is the backbone of the peptide straight?

  17. Are the ends of the peptide buried or exposed?

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