MHC molecules Flashcards
what is a MHC
tightly linked cluster of genes
which chromosome is the MHC present on?
6
where is the code for MHC protein found
on the surface of cells
what is the function of MHC molecules
to bind peptide fragments from the cell
and to display them on the cell surface for recognition by the appropriateimmune cells
what is the 2 major types of MHC protein molecules
CLASS 1
CLASS 2
what is class 1 ,MHC
present on everynucleated cellin an organism
what is class 2 MHC
are restricted to cells of theimmune system- macrophages, dendritic cells and B cells
how is MHC1 presentation done?
proteasomes generate peptides from all proteins present within the cell
Peptide fragments are transported to the endoplasmic reticulum, where they are loaded onto the MHC class I molecule
MHC class I-loaded complexes are transported to the cell surface, where they are presented to CD8+ T cells
what are proteasomes
– enzymes involved in breaking down intracellular proteins
Aminopeptidases
enzymes that catalyse the cleavage of amino acids
what do MHC molecules display?
‘self’ peptides and foreign peptides (derived from invading pathogens/abnormal cells)
what does the immune system do in terms of mhc molecules?
monitors the amount of MHC-presented antigens
cancerous cells that often display increased amounts of
self- antigens
how is mhc 2 presentation done? 1/4
Extracellular antigens are taken up within phagosomes by APCs
how is mhc 2 presentation done? 2/4
Phagosomes fuse with lysosomes, which contain proteolytic enzymes that cleave the phagocytosed proteins into small peptides
how is mhc 2 presentation done? 3/4
MHC class II molecules are delivered to the phagolysosomes and loaded with peptides
