IMED2001 Study Guide - Final Guide: Cd74, Mhc Class Ii, Tapasin
30 Jun 2018
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IMED2001 Revision Notes 7
HLA = human MHC
-class 1 !
-= has beta 2 to bind to microglobulin!
-binds to shorter peptides!
-Class 2 !
-= NO beta 2 to bind to microglobulin!
MHC HIGHLY POLYMORPHIC:
-organ transplant difficult because need to match otherwise rejected!
Where they get peptide antigen from:
Class 1 !
= endogenous source (virus that infected cell so viral peptides in cytosol)!
Class 2 !
= exogenous!
MHC CLASS 1:
Ubiquitination!
-it is like a tag!
-similar to opsonins!
-tells proteasome to degrade it!
-(viral proteins into peptides)!
-then shorter peptides have to be brought into ER!
-via TAP !
-Then MHC attach to TAP !
-**by tapasin!
-Peptide then loaded onto MHC MHC complex (MHC and peptide)!
-Then brought to GA!
-Then from GA, transported via exocytic vesicle onto the CSM!
-To be presented to T cells.!
Endogenous peptide -> chopped up by proteasome -> then loaded via TAP and tapasin -
> onto MHC class 1 within ER -> MHC class 1 peptide complex from ER -> GA ->
transported to CSM -> peptides presented to CD8+ T cells
MHC CLASS 2:
-NO PROTEASOME!
-degradation done by lysozyme!
-MHC class 1 is proteasome!
-Long peptide cleaved by lysozyme !
Document Summary
= has beta 2 to bind to microglobulin. = no beta 2 to bind to microglobulin. Organ transplant di cult because need to match otherwise rejected. = endogenous source (virus that infected cell so viral peptides in cytosol) Then shorter peptides have to be brought into er. Peptide then loaded onto mhc mhc complex (mhc and peptide) Then from ga, transported via exocytic vesicle onto the csm. Endogenous peptide -> chopped up by proteasome -> then loaded via tap and tapasin - > onto mhc class 1 within er -> mhc class 1 peptide complex from er -> ga -> transported to csm -> peptides presented to cd8+ t cells. Invariant chain (longer version of clip: er: First thing that binds to mhc2 is invariant chain peptide: left er in exocytic vesicle. Li needs to be cleaved: once cleaved. Fuses with vesicle that contains fragmented peptide. (cleaved from lysozyme: when two vesicle fused.
