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22 Cards in this Set
- Front
- Back
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Why is the major histocompatibility complex also known as human leukocyte antigen(HLA) complex?
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Sets of highly polymorphic genes whose final protein products regulate the immune responses, especially antigen presentation to T cells.
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What chromosome contains the MHC?
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Short arm of chromosome 6.
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What are the two classes of MHC. What sets of HLA genes are associated with each class?
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Class 1: HLA-A/HLA/B/HLA/C
Class-2: HLA-DP/HLA-DQ/HLA-DR The individual HLA gene encode for the alpha chain of the MHC class 1 molecule, and the alpha and beta chains of the MHC Class 2 molecule. |
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How are MHC inherited and expressede?
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Each person has 2 haplotypes(2 sets of MHC) with one paternal set and one maternal set expressed in a codominant gene fashion(both paternal and maternal genes are expressed).
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How many MHC molecules can an individual make?
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2 MHC haplotypes X 2 MHC classes X 3 HLA types in each class= 12 MHC molecules.
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Name of the HLA haplotype(s) associated with each of the following diseases:
Multiple sclerosis Type 1 insulin dependent DM Rheumatoid arthritis Hashimoto's Hemachromatosis Graves' Seronegative spondyloarthropathies(ankylosing spondylitis, Reiters syndrome |
MS= HLA-DR2
DM type 1=HLA-DR3/DR4 Rheumatoid arthritis=HLA-DR4 Hashimoto's=DR3/DR5 Hemachromatosis-HLA-A3 Grave's- HLA-B8/HLA-DR3 Spondyloarthropathies-HLA-B27 |
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What is the importance of MHC class 1 and 2 proteins?
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Enable T cells to recognize foriegn antigens
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What is the structure of MHC class 1?
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Structure= 1 X (alpha heavy chain)+ 1 X (beta 2-microglobin)
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Describe the alpha heavy chain's structure. Where is the peptide binding groove?
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Three extracellular domains(alpha 1 and 2 form the peptide binding groove) and a single transmembrane domain.
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The beta 2 microglobin is not encoded by a gene in the MHC region. What is its function?
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Stabilizes MHC class 1 expression on the cell surface.
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What are MHC class 1 proteins and where are they found?
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Membrane glycoproteins on the surface of all nucleated cells and platelets.
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Red blood cells lack MHC class 1 proteins. TRUE/FALSE
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TRUE
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What is the function of MHC class 1 proteins?
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They bind intracellular proteins(both self and foriegn) and present them to cytotoxic T lymphocytes(CTLs)
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How do proteins become associated with MHC class 1 molecules?
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Proteins in cytosol are routinely degraded and transported via a peptide transporter(TAP complex) into the endoplasmic reticulum, where they bind to newly synthesized HLA class 1 proteins.
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What are sources of foriegn proteins associated with MHC class 1 molecules? What happens to cells presenting foriegn antigens?
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Viruses, intracellular bacteria and parasites, or neoantigens(the cell is atumor cell). These cells are lysed by CTLs.
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What is the structure of MHC class 2 molecules?
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Structure= 1 X (alpha chain) + 1 X (beta chain)
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Describe the structure of the alpha and beta chains.
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Each has 2 extracellular domains(alpha1 and2) and one transmembrane domain(alpha3). peptide binding groove is formed by the alpha1 extracellular doamin of chain.
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Where are MHC class 2 molecules expressed?
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APCs- monocytes/macrophages, dendritic cells, B lymphocytes, Langherhans cells, activated T cells, and activated endothelial cells.
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Where are MHC class 2 molecules expressed?
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APCs- monocytes/macrophages, dendritic cells, B lymphocytes, Langherhans cells, activated T cells, and activated endothelial cells.
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MHC class 2 molecules are cell surface proteins.
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Bind and present exogenous peptides to CD4+ helper T lymphocytes
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How are MHC class 2 molecules loaded with peptide?
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Vesicles containing endocytosed and cleaved extracellular protein fragments fuse with vesicles containing MHC class 2 molecules. In these vesicles, they are loaded onto MHC class 2 and are transported to the surface.
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What prevents MHC class 2 molecules from binding peptides before fusion with vesicles containing endocytosed antigen?
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The invariant chain blocks the peptide binding groove of MHC class 2 molecule as it is transported through the cell. The invariant chain is degreded within the vesicle that contains processed antigen for loading.
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