Test 1: lecture 6 T cell part 1 Flashcards
what does T cell receptor look like?
two classes of T cell receptors
alpha, beta
gamma, delta
alpha beta T cell
Their TCR is composed of an a and a b chain. These are very similar in all mammals, birds and fish. It is the a and b chains that determine the specificity of a T cell.
most known type of T cell
gamma delta T cell
•These differ in antigen recognition and function in different species.
–Often more abundant in tissues than circulation (in mice and humans)
–Share properties with innate cells (e.g. NK cells)
–Recognition of antigens differs from ab T cell
–Higher frequencies in blood of ruminants, pigs, poultry
how to diversify TCR
multiple V genes in germ line
random recombination
junctional and insertional variability
TCR complex are required for __
signaling
to get TCR to the surface of the cell
____ are a complex of proteins that help TCR signal and get to surface of T cell
CD3
___ heterodimer of the highly variable a and b chains (or g and d chains) expressed at the cell surface as a complex with the invariant CD3 chains.
Disulfide-linked
mature alphabeta T cells express ___ or ___
CD4 or CD8
___ molecules bind to MHC gene products expressed on antigen presenting cells
CD4 CD8
___ enhance T cell-antigen presenting cell interaction and help with cell signal transduction
CD4 and CD8
CD8 binds to
aplha 3 domain of MHC 1
CD4 binds to ___
beta 2 domain of MHC class 2
CD8 binds to the ___ of the MHC ___
alpha 3
class 1
CD4 binds the ___ domain of MHC class ___
beta 2
MHC class 2
MHC class 1 is made of what domains
alpha 1,2,3
Beta 2 microglobulin
alpha 3 binds to CD8
MHC class 2 is made of domain ___
alpha 1,2
beta 1,2
B2 binds to CD4
what does MHC stand for
major histocompatibility complex
(class 1 or class2 seen by T cells)
•Genes encoding Class I and Class II molecules are encoded in ___
the MHC.
what can T cells see
cell surface peptides of antigens presented by cells that express MHC antigens
Antigen recognition by T cells requires ___ and presenting cells that express MHC molecules
peptide antigens
there are a ___ number of genes that encode for MHC
limited (small amount)
___ = many genes
polygenic
___ = many shapes
polymorphic
–Variation at the single genetic locus and its product within a species; the individual variants at that locus are called ___
alleles
•Many alleles means that an individual is likely to be ___ at these loci
heterozygous
•Both alleles are expressed in the cell- termed ___ expression.
codominant
class 1 MHC
class II MHC
which MHC can see peptides longer then 10 amino acids?
class II
class I shape is limited to 9 amino acids or smaller
Peptides bound to a particular type of MHC class I molecule have conserved patterns of ___
amino acids
A common sequence in a peptide antigen that binds to an MHC molecule is called a ___
motif
Amino acids common to many peptides tether the peptide to structural features of the MHC molecule. These are called ___
anchor residues
Tethering amino acids need not be identical but must be ___
Y & F are aromatic
V, L & I are hydrophobic
related
Side chains of anchor residues bind into ___ in the MHC molecule
pockets
Different types of MHC molecule bind peptides with different ___ of conserved amino acids
patterns
what class of MHC has anchor residues that are not localised at the N and C termini
class II
peptide can be any length due to shape of MHC class II
how can MHC bind to so many different types of peptides?
• Use a small number of anchor residues to tether the peptide this allows different sequences between anchors and different lengths of peptide
T cells can only be activated by interaction between the antigen receptor and peptide antigen in an ___ molecule
MHC
Without T cells there can be no effective ___ response
immune
The MHC has evolved two strategies to prevent evasion by pathogens
More than one type of MHC molecule in each individual
Extensive differences in MHC molecules between individuals
___ :Several MHC class I and class II genes encoding different types of MHC molecule with a range of peptide-binding specificities.
polygenism
Variation >1% at a single genetic locus in a population of individuals
POLYMORPHISM
___ genes are the most polymorphic genes known
MHC
POLYMORPHISM
Variation >1% at a single genetic locus in a population of individuals
The type and variant MHC molecules ___ in the lifetime of the individual
do not vary
The diversity in MHC molecules exists at the ___ level
This sharply contrasts with the diversity in T and B cell antigen receptors which exists within the individual
population
you have the same MHC your whole life, where the types of T and B cells change depending what you are exposed to
