Cell Mediated (II) Flashcards
What are MHC made of
Glycoproteins with domains
Which cells do MHC I activate
CD8 for intracellular / endogenous peptides
Which peptides do MHC II hold
Exogenous (endocytosed then cleaved by proteases)
Which 3 alleles of HLA genes encode for MHC I (3 a , 1 B2)
HLA - A,B,C
Which alleles encode for MHC II (2a,2b)
HLA - dp,dq,dr
Which chromosome holds HLA genes
16
Which cells is MHC 1 on
All nucleated cells (any virally infected can express them)
What makes MHC so polymorphic
Many alleles for the A chain
HLA A,B,C all have different a chains which make up the MHC 1
What is difference between MHC 1 peptide vs MHC 2
Shorter (8-10 AA long)
Which part of MHC 1 isn’t polymorphic
B2 micro globulin
How do A1,a2 on MHC 1 bind to 8-10 AA peptide
H bonds or ionic bonds
Which structure makes up the A1,A2 domains on MHC 1
2x beta sheets
2 x alpha helixes
(Highly polymorphic)
How is a3,B2 different to A1,a2
Ig like - only beta chains
Low polymorphisms
How long is polypeptide that A1,B1 bind to in MHC II
13-24 AA long (longer)
Where is the highest polymorphisms in MHC II of the dp,dq and dr alleles
A1, B1 (peptide cleft)
A2, B2 is ig like
What processes proteins made by viral cells which then make up MHC 1
Proteasome
What transfers peptide fragments processed after proteasome to the ER (where MHC 1 lay)
TAP (in all nucleated cells)
What covers the cleft (A1,B1) of MHC II before the endocytosed peptide can bind
Invariant chain
Where do MHC II lay before the vesicles fuses with the peptide from proteases
ER and Golgi
What is on T cells to allow for cell stimulation due to small cytoplasmic domain of tcr
Cd3 complex
What 2 types of cd3 are there
Gamma epsilon
Gamma delta
What does the CD3 have on it to allow signalling to T cell when T cell is bound with MHC
ITAMS
What is CD8 and CD4
Gp needed to keep MHC close to T cell for activation
What makes up CD8
Crossing of an alpha and beta
Interacts with MHC 1
What makes up CD4 which interacts with MHC II
D1,2,3,4
Why is polymorphisms of peptide cleft good
To allow broad range of peptide T cells can be activated by
Why does polymorphisms in MHC cause graft rejection
Other persons HLA genes could be different so could be seen as foreign
What is MHC expression induced by
IFN
Why can a peptide be presented same time as another
MHC expression is codominant
