Major Histocompatibility Complex MHC Flashcards
MHC are
PM bound glycoproteins
MHC fn
to present peptide ligands to T cells
MHC I is found on
all nucleated cells (meaning not on RBC)
MHC II are found on
only antigen presenting cells such as dendritic cells, macrophage and B cells
MHC I how many peptides
composed of 2 polypeptides
MHC I larger peptide
larger one called alpha chain; compose of 3 external domains (a1,a2,a3), a transmembrane region followed by a cytoplasmic region
MHC smaller peptide
called beta2-microglobulin. noncovalently bound to the alpha chain
Beta2-microglobuline and alpha3 domains similarities
in structure and sequence homology to the constant region of immunoglobulins, called immunoglobulin-like domain
alpha1 and alpha2 form a
peptide binding cleft
MHC II components
2 diff polypeptides, alpha and beta chain, non covalently associated.
what are the alpha and beta chains of MHC II composed of
2 external domains, a transmembrane region and a cytoplasmic region. a2 and b2 domains are Ig-like domains.
fn of MHC
present antigenic peptides to T cells
MHC I presents antigenic peptides derived from
cytoplasmic proteins to CD8 T cells. these proteins could be viral or bacterial
proteosome
enzyme complex that degrades endogenous proteins
TAP
trasnmembrane protein that transpoorts resulting peptides into the RER
what happens to MHC I once inside the RER
peptide can bind to MHC I. MHC I-peptide complex is then transported to cell’s PM
fn of MHC II
to present exogenous peptides to CD4+ T cells. antigen presenting cells take up exogenous antigen by phogocytosis/endocytosis
invariant chain (Ii) fn
in RER, protein that binds too peptide binding cleft of MHC II to prevent endogenous peptides from binding
where is the MHC II-invariant chain transported to
phagosome/endosome, where invariant chain is degraded. exogenous peptide binds to cleft. MCH II-peptide complex transported to PM
is binding of peptides to MHC specific
no
