Lecture 11 Antigen Presentation to T cells Flashcards
Antibodies recognize and bind _____ protein structures
intact (native) - visible on protein surface
TCR bind a complex of _____ fragment and _______ on the cell surface
antigen; self-molecule
The protein that _____ bind can be continuous or discontinuous
antibodies
______ binds epitopes that are Linear and buried in the protein
TCR
____ cells are virus specific
cytotoxic T cells
some highly specialized cells do not have a lot of _____ because they do not renew
MHC I
Cytotoxic T cell function
kill cells that present a viral protein on MHC I
CD4 cells function
recognize MHC II on infected macrophages, TH1 activate macrophage to destroy bacteria inside
Follicular helper T cell function
TFH cells recognize antigen on B cells and activate them to proliferate and differentiate into plasma cells
Extracellular material is taken up by
phagocytosis or endocytosis
______ surround components in cytosol and deliver them to lysosomes
autophagosomes
Viruses are degraded in the _____ and loaded onto MHC I. The effect when presented to ___ cells is death.
cytosol; CD8+ T cells
Bacteria can be taken up in ______ and their antigens are presented via MHC II. The effect when presented to _____ cells is to activate the macrophage to kill the bacteria.
endosomes; CD 4+
Proteins can be delivered to a cell from extracellular pathogens via _____ in B cells. These can be presented on ____ to CD4+ cells to stimulate B cells to produce antibodies
endocytosis; MHC II
Virus uses ____ to make proteins
cell machinery
Viruses are synthesized in ______ and their peptide fragments are bound by MHC I in ____.
cytosol; ER
proteins tagged by ubiquitin go through _____ to break up into peptides
proteasome
proteasome has _______ core and 2 ____ regulatory caps
20S catalytic core; 19S
The ______ recognizes polyubiquitin
19S regulatory cap
______ cause covalent tagging of K48 linked polyubiquitin chains
E3 ligase
peptides broken down by proteasome can go through ______ from cytosol to ER
TAP 1 and TAP 2 channel
going through TAP channel is ________ dependent
energy
partly folded MHC I alpha chain bind to _____ until beta2 microglobulin binds
calnexin
When beta2m binds, calnexin is released and MHC I is _____ and binds to _______ (TAP associated)
partly folded; tapasin
_____ (forms a heterodimer with tapasin) and _______ bind to MHC I
ERp57; calreticulin
_____ can bind to MHC I and once proteins bind, folding is completed, MHC is released from _____ complex and exported to cell membrane
DRiPs (defective ribosomal products); TAP
in early endosomes with bacterial antigens, there is _____ pH
neutral
in the presence of proteins, there is a signal to _____ pH through _____ of H+
lower; influx
The ______ of vesicles activates proteases to ________ antigens into peptide
acidification; degrade
vesicles with peptides can fuse with vesicles containing ____
MHC II
MHC II is made in the _____ and ____ is bound when its exported into vesicle to stabilize
ER; CLIP (part of invariant chain)
____ binds to MHC II in ER
Invariant chain Ii
Ii is cleaved after transport into ________ by noncysteine proteases to leave _____
acidified vesicle; LIP22
LIP22 is cleaved by cysteine proteases to yield _____
LIP10
_____ targets MHC II to the endosomal pathway
LIP10
Cleavage of LIP10 yields _____ in the acidified vesicle (late endosomes)
CLIP
_____ blocks pathogen peptides from binding to MHC II
CLIP
____ binds to MHC II:CLIP complex, releasing CLIP
HLA-DM
DCs can take up ____ bodies (virus infected cells) and is loaded onto MHC I to activate ____ to disengage and move around body
apoptotic; cytotoxic T Cells
Cross-presentation/cross-priming
exogenous pathway for loading pathways onto MHC I
