Linking Innate and Adaptive Immunity 3 Flashcards
what do TCRs recognize? where?
peptide-MHC complexes on the surface of APCs
what is an immunological synapse?
T cell:APC contact, with the TCR complex
what are the 4 components of the TCR complex? describe each component’s location in the complex
- TCR –> in the middle
- CD3 –> 1 on either side of TCR
- zeta chain –> 2 inside cell
- ITAM –> on intracellular part of CD3 and zeta chains
what is ITAM?
Immunoreceptor Tyrosine-based Activation Motif
what does the TCR complex trigger?
intracellular signaling
what type of molecule is TCR?
HETERODIMER
what type of proteins are involved in TCR?
transmembrane proteins
is TCR secreted?
no, it is membrane-bound
what are the 2 main types of TCR? which is most common?
- alpha-beta TCR (most common)
- gamma-delta TCR (<10%)
what are the 2 types of chains on the most common TCR?
- ALPHA
- BETA
what does clonotypic mean?
the cells of a given clone all have identical receptors
what are the 2 main subunits of each chain?
- Variable (V)
- Constant (C)
how many TCR and BCR are possible? why?
billions! to allow for increased specificity
how does the number of adaptive immune receptors compare to the number of innate immune receptors? why?
there are <100 innate immune receptors (PRRs) because they don’t need to be very specific
BCR and TCR genes undergo __________
BCR and TCR genes undergo DNA rearrangement
what are the 4 gene segments of BCR and TCRs?
- Variable (V)
- Diversity (D)
- Joining (J)
- Constant (C)
what are gene segments?
short DNA sequences
what domains are in the alpha chain?
V, J, C
what domains are in the beta chain?
V, D, J, C
where does TCR rearrangement occur?
in the thymus
what is another term for gene rearrangement?
somatic recombination
what is somatic recombination/gene rearrangement?
recombination of gene segments in TCR genetic loci to make a functional gene
describe gene rearrangement for alpha chain
1 V, J, and C are selected in the DNA to be transcribed and translated into an alpha chain
describe gene rearrangement for beta chain
1 V, D, J, and C are selected in the DNA to be transcribed and translated into a beta chain
how many variations of TCRs are possible? how is this variability achieved?
billions of variations possible
many combos of each subunit are possible, and many combos of alpha and beta chains are possible