MHC 1 Flashcards
Which part of an antibody do T cell receptors resemble?
The FAB fragment
What are the two main components of a TCR?
Alpha chain and beta chain
Where are TCRs always found?
Membrane bound
Where does variation in TCRs come from?
Hyper-variable loops
How many variable loops does each part of a TCR contribute?
Alpha chain = 3 CDRs
Beta chain = 3 CDRs
What is CD3?
Other proteins that are part of the TCR signalling complex
What are the diff CD3 subunits?
Delta, epsilon, gamma, zeta
What is the role of CD3?
Signalling to the inside of the cell once an antigen has bound to the TCR
Why does the CD3 need to do the signalling?
The TCR on its own does not have any signalling domain/capability
Difference in recognition of antigens between antibodies and T cells?
Antibodies can recognise native antigens on the surface of bacterium etc, whereas T cells can only recognise antigens that have been processed and presented on MHC molecules
What are the two classes of MHC?
1 and 2
Process of presenting an antigen to a t cell?
Proteins are broken down into peptides, peptides are loaded onto MHC, t cell receptor complex of MHC molecule and peptide
What do t cell receptors recognise?
The complex of an MHC molecule and a peptide
How can a TCR recognise an antigen sometimes but not others?
If the antigen is presented on a diff MHC molecule the t cell receptor may not recognise the complex
What are the two types of t cell?
CD8 and CD4
What makes a t cell a CD8 t cell?
They express a TCR with a CD8 co receptor
What makes a t cell a CD4 t cell?
They express a TCR with a CD4 co receptor
Which MHC molecule do CD8 t cells recognise?
MHC class I
Which MHC molecule do CD4 t cells recognise?
MHC class II
What does CD8 and CD4 do?
Strengthens the interaction between the T cenn and the antigen presenting cell
What is CD8 and CD4 not involved in?
Antigen binding
Where is the transmembrane domain for MHC class I?
Alpha subunit
Where are the transmembrane domains for MHC class II?
Alpha and beta subunits
Makeup of MHC class I?
Alpha subunit w/ 3 domains (alpha 1, alpha 2, alpha 3), beta 2 microglobulin
Which domains in MHC class I form the peptide binding groove?
ALpha 1 and alpha 2
Role of beta 2 microglobulin?
Stabilises the MHC class I
Which domains in MHC class II form the peptide binding groove?
Beta 1 domain and alpha 1 domain
How large can the residues in the peptide binding groove of MHC class I be?
8-10 residues
How long are the peptides that MHC class I bind to?
8-10 residues
What is different between diff types of MHC molecules?
Different peptide selectivities
Thy have preference for the type of sequence, not a specific sequence
