Flashcards
MHC (Immunology)
Cards in this deck (17)
- 1What is the purpose of MHC?To provide a way to allow T cells fo be a bale to differentiate between infected and non-infected cells.
Antibodies are useless once the pathogen has entered a cell. - 2What do the two classes of MHC present to?MHC 1 - CD8 T Cells
MHC 2 - CD4 T Cells - 3What domains make up MHC 1?Alpha 1
Alpha 2
Alpha 3
Beta 2 microglobulin - 4Which domains are constant in MHC 1?alpha 3
beta 2 - 5Which domains create the peptide binding groove?Alpha 2
Alpha 1 - 6What are the sizes of the peptides that can be presented by MHC 1?8-10 amino acids in length
- 7Draw a diagram of MHC 1use notes
- 8What domains make up MHC 2?alpha 1
alpha 2
beta 1
beta 2 - 9What are the constant regions in MHC 2?alpha 1 and beta 1
- 10What is the size of the peptides that can be displayed by MHC 2?12-20 amino acids long
- 11Draw a diagram of MHC 2use notes
- 12How are the MHC classes expressed?MHC 1 is found on most cells
MHC 2 tends to only be found on B cells or antigen presenting cells such as dendritic cell. Such cells will present both MHC 1 + 2.
It is rare to see MHC 2 without MHC 1 - 13Describe the structure of a T cell receptorBeta chain
Alpha chain
CD3 polypeptide chain (always present)
Associated accessory molecules which recognise MHC class - 14Outline the endocytic pathway for antigen presentation-Exogenous, extracellular antigen is ingested by endocytosis or phagocytosis
-The antigen is broken apart by endosomes and lysosomes
- The antigen is broken apart into peptides which are displaed upon MHC 2
This pathway is mainly for APCs - 15Outline the cytosolic pathway for antigen presentation-Endogenous, intracellular antigen
-Maybe a virus or cancer
-The virus hijacks cellular machinery
-Viral protein is produced and some is degraded
-the degraded protein is displayed via MHC 1 - 16Outline MCH class 1 processing-Pathogenic fragments are broken down and are taken up into the endoplasmic reticulum via the TAP transporter at a size of 8-10 amino acids
-During this time the MHC complex is made
-In the first stage it is attached to the chaperone protein Calnexin
-Once the B2 domain attaches, two new chaperone proteins attach, ERP 57 and Calreticulin
-These two proteins work to block the peptide binding groove to prevent normal proteins binding to it
-They also move the complxe towards the TAP transporter
-At the TAP transporter, the enzyme Tapasin removes the chaperone which enables the pathogen peptide to bind
-The complex is now taken to the cell membrane via an endosome and presents to a CD8 cell - 17Outline MHC 2 processing- The pathogenic anitgen is broken down and taken up into a lysosome where it is held
-Meanwhile the MHC is built
-To prevent normal proteins binding to it, the chaperone protein CD74 binds and blocks the peptide binding site
- The CD74 eventually degrades into a protein called CLIP
-The complex and the lysosome fuse and the foreign peptide binds to the groove
-The complex is then taken to the membrane
-This all occurs in the cytosol, differing to MHC 1 processing
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- USMLE Medicine Flashcards on MHC (Immunology), created by Chandler Garrett on 24/08/2016.
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- Chandler Garrett
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- Created by Vay · Apr 10, 2015
- Copied by Chandler Garrett · Aug 24, 2016
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