Flashcards in MHC class I and antigen recognition Deck (105)
Why does there have to be a rapid response to MHC class I?
viral infection cycles can be short-4 hours, so need to identify and kill infected cell before virus release
What breaks up the proteins in to peptides to go into the endoplasmic reticulum?
What is the transporter for peptides into the endoplasmic reticulum?
TAP1 and TAP2
What cells are capable of cross presentation?
DCs and macrophages
In addition to the structural cell surface, what else does the HLA region encode?
peptide loading functions- TAPS and LMPs
What is TAP?
transporter associated with antigen presentation
How are pMHC complexes from the ER to the plasma membrane?
What has to happen to endogenous proteins before they can be fe to the proteasome?
What is a proteasome?
multicatalytic protease complex made up of around 28 subunuts
How does gamm inteferon affect the proteasome?
induces expression of alternative beta subunits creating an immunoproteasome
What alternative beta subunits does IFNy induce in the proteasome?
PSMB10; LMP2 and LMP7; LMP10; PA28
What is the function of proteasome activating molecule (PA28) iniduced by gamma interferon?
increased release of cleaved peptides
Where do immunoproteasomes preferentially cleave peptide bonds?
after hydrophpboic or basic residues
Why do immunoproteasome preferntially cleave after hydrophobic or basic residues?
preferred by MHC class I for binding
What type of transporter is TAP?
ATP dependent (ATP binding cassette- ABC family of transporters)
What are carbxoxyl terminla amino acids ?
hydrophobic or basic
What is the specificty of a given allelic MHC molecule for different peptides?
can bind numerous different peptides; each MHC allele binds a different set of peptides
What is the function of the diversity of MHC I,II within a species?
helps protect from new pathogens
Where are most polymorphic residues located in the MHC molecule?
in the peptide binding cleft
What is found within the deep pockets of the MHC molecules?
What is the function of the anchor residues?
where peptides are bound
What is the converved anchor residue?
hydrophobic (basic occasionally)
What amino acid sequence does the MHC-I groove correspond to?
contiguous amino acid sequence formed by the N-terminal region of a single subunit or heavy chain
What amino sequence does the MHC-II groove correspond to?
juxtaposition of hte N-terminal regions of 2 MHC encoded alpha and beta chains
What is the difference between the membrane-proximal regions of the MHC-I and MHC-II molecules?
although in both it is a conserved domain that are homologous to the Ig constant region, in MHC-I, one is the heavy chain and the other is beta microglobulin, whereas in MHC-II there is an alpha subunit and beta subunit
What mediates proteolysis in the cytosol?
What is the function of cross-presentation?
allows dendritic cells to present antigen to CD8 T cells even if the virus does not directly infect dendritic cells
What is the activation of naive T cells through cross presentation called?
What is the structure of the proteasome?
20S catalytic core which consists of 4 multiple subunit rings with 2 19S regulatory caps on either end