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Major Histocompatability Complexes (view source)
Revision as of 12:07, 28 August 2008
, 12:07, 28 August 2008New page: {{toplink |backcolour = FFE4E1 |linkpage =Immunology - WikiBlood |linktext =IMMUNOLOGY |maplink = Adaptive Immune System (Concept Map) - WikiBlood |tablelink = Adaptive Immune System (Tab...
{{toplink
|backcolour = FFE4E1
|linkpage =Immunology - WikiBlood
|linktext =IMMUNOLOGY
|maplink = Adaptive Immune System (Concept Map) - WikiBlood
|tablelink = Adaptive Immune System (Table) - WikiBlood
|sublink1 =Adaptive Immune System - WikiBlood
|subtext1 =Adaptive Immune System
|pagetype =Blood
}}
==Structure and Function of MHC Class I==
===Structure===
* MHC class I is expressed on virtually all nucleated cells.
* MHC class I consists of a membrane-associated heavy chain bound non-covalently with a secreted light chain.
** Heavy chain:
*** Made up of three distinct extracellular protein domains.
**** α1, α2 and α3.
*** The C- terminus is cytoplasmic.
** Light chain:
*** Known as β2-microglobulin.
*** Similar in structure to one of the heavy chain domains.
*** Not membrane associated.
**** But binds to the α3-domain of the heavy chain.
* The MHC class I domains are structurally and genetically related to immunoglobulin and TcR domains.
** The outer domains (α1 and α2) are like the variable domains.
** The α3 domain and β2m are like thrconstant domains.
* MHC class I molecules are folded to form specific 3-dimensional structures.
** The α1 and α2 domains are folded to produce an antigen-binding groove.
*** This groove can bind molecules of a limited size only.
**** 8-10 amino acids.
**** This limits the size of epitope seen by the T-cell receptors.
===Function===
* MHC class I molecules bind antigenic peptides derived from within the cell and present these to the T-cell receptors of CD8+ T-cells.
** E.g. virus-encoded antigen.
* Endogenously produced proteins are produced in the cell cytoplasm.
** Intracellular pathogens utilise this cellular metabolic machinery for protein synthesis.
** Many of the proteins synthesised are not used and are re-utilised by the cell.
*** Peptides from these proteins are transported to the Golgi apparatus by specific transporter molecules.
*** These peptides then interact with newly synthesized MHC class I molecules.
* Only MHC class I that is associated with peptide will be expressed at the surface.
** The immune system is therefore able to see antigen from intracleeular pathogens.
|backcolour = FFE4E1
|linkpage =Immunology - WikiBlood
|linktext =IMMUNOLOGY
|maplink = Adaptive Immune System (Concept Map) - WikiBlood
|tablelink = Adaptive Immune System (Table) - WikiBlood
|sublink1 =Adaptive Immune System - WikiBlood
|subtext1 =Adaptive Immune System
|pagetype =Blood
}}
==Structure and Function of MHC Class I==
===Structure===
* MHC class I is expressed on virtually all nucleated cells.
* MHC class I consists of a membrane-associated heavy chain bound non-covalently with a secreted light chain.
** Heavy chain:
*** Made up of three distinct extracellular protein domains.
**** α1, α2 and α3.
*** The C- terminus is cytoplasmic.
** Light chain:
*** Known as β2-microglobulin.
*** Similar in structure to one of the heavy chain domains.
*** Not membrane associated.
**** But binds to the α3-domain of the heavy chain.
* The MHC class I domains are structurally and genetically related to immunoglobulin and TcR domains.
** The outer domains (α1 and α2) are like the variable domains.
** The α3 domain and β2m are like thrconstant domains.
* MHC class I molecules are folded to form specific 3-dimensional structures.
** The α1 and α2 domains are folded to produce an antigen-binding groove.
*** This groove can bind molecules of a limited size only.
**** 8-10 amino acids.
**** This limits the size of epitope seen by the T-cell receptors.
===Function===
* MHC class I molecules bind antigenic peptides derived from within the cell and present these to the T-cell receptors of CD8+ T-cells.
** E.g. virus-encoded antigen.
* Endogenously produced proteins are produced in the cell cytoplasm.
** Intracellular pathogens utilise this cellular metabolic machinery for protein synthesis.
** Many of the proteins synthesised are not used and are re-utilised by the cell.
*** Peptides from these proteins are transported to the Golgi apparatus by specific transporter molecules.
*** These peptides then interact with newly synthesized MHC class I molecules.
* Only MHC class I that is associated with peptide will be expressed at the surface.
** The immune system is therefore able to see antigen from intracleeular pathogens.