Immunology 6 Flashcards
MHC class 1 is expressed in ..?
All nucleated cells
MHC class2 is expressed in …?
professional APCs
What domain of MHC class 2 binds CD4?
beta domain
What domain of MHC class 1 binds CD8?
alpha domain
TCR binds both the antigen and MHC molecule. True or False?
True
Which of MHC Class-1 and Class-2 has a relatively closed groove so the binding occurs in pockets at the ends of the groove?
Class-1
Describe the MHC class-2 antigen binding groove.
The groove is much more open so can accommodate bigger peptides and bind all along the length of the binding site.
Where are peptides for MHC class-2 derived from?
Extracellular peptides.
(MHC-2 Synthesised in cell, translocate to ER, vesicles bud off and bind with peptides in antigen-processing compartment)
Where are peptides for MHC class-1 derived from?
Intracellular peptides.
Often from when a cell is infected with a virus.
Where are viral antigen broken down for presentation on MHC class-1?
proteasome (peptide then binds to class 1 molecule in golgi and transported to surface.)
What does interferon-gamma turn the proteasome into?
The immunoproteosome.
This contains additional subunits.
What additional subunits does immunoproteosome contain that proteasome doesn’t?
LMP2, LMP7, MECL1
These change specificity of cleavage.
What is the difference in function between immunoproteosome and proteasome?
There is an increased cleavage after hydrophobic residues so there are more peptides with C terminal hydrophobic residues which favours binding to MHC class 1.
What is TAP?
Transporter for antigen processing. Transport degraded peptides from proteasome to endoplasmic reticulum
What does Calnexin do?
Stabilises MHC class 1 heavy chain until beta-globulin binds and releases calnexin.