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Major Histocompatability Complexes (view source)
Revision as of 13:18, 9 September 2008
, 13:18, 9 September 2008→The Genetics of the MHC
[[Image:Location of Polymorphic Residues 1.jpg|thumb|right|150px|Location of Polymorphic Residues - Copyright Prof Dirk Werling DrMedVet PhD MRCVS]]
[[Image:Location of Polymorphic Residues 1.jpg|thumb|right|150px|Location of Polymorphic Residues - Copyright Prof Dirk Werling DrMedVet PhD MRCVS]]
=The Genetics of the MHC=
=The Genetics of the MHC (Polymorphism)=
*Each individual has 6 types of MHC
*MHC molecules are co-dominantly expressed
*The combination of alleles in a chromosome is called an '''MHC Haplotype'''
* Different individuals have different critical amino acids within the MHC
* Different individuals have different critical amino acids within the MHC
** I.e. different amino acids that determine peptide binding
** I.e. different amino acids that determine peptide binding
** This variation is termed '''MHC polymorphism'''
** This variation is termed '''MHC polymorphism'''
**Each polymorphic variant is called an '''allele'''
*Both type I and type II MHC molecules are highly polymorphic
*Both type I and type II MHC molecules are highly polymorphic
**Most polymorphic regions of class I are in the alpha 1 and alpha 2 domains
**Most polymorphic regions of class I are in the alpha 1 and alpha 2 domains
**Most polymorphic regions of class II are in the alpha 1 and beta 1 domains
**Most polymorphic regions of class II are in the alpha 1 and beta 1 domains
*Most polymorphisms are point mutations
* There are millions of variations in antibodies and TCR
* There are millions of variations in antibodies and TCR
** However, with MHC there is very limited variation between molecules
** However, with MHC there is very limited variation between molecules
*Allelic variation within the MHC molecule occurs at the peptide binding site and on the top or sides of the binding cleft
*Allelic variation within the MHC molecule occurs at the peptide binding site and on the top or sides of the binding cleft
*Polymorphisms and polygenism in the MHC protects the population from pathogens evading the immune system
* MHC polymorphism has been best studied in the human
* MHC polymorphism has been best studied in the human
[[Image:Location of Polymorphic Residues 2.jpg|thumb|right|150px|Location of Polymorphic Residues - Copyright Prof Dirk Werling DrMedVet PhD MRCVS]]
[[Image:Location of Polymorphic Residues 2.jpg|thumb|right|150px|Location of Polymorphic Residues - Copyright Prof Dirk Werling DrMedVet PhD MRCVS]]
==In the Human==
==In the Human==
* Humans express:
* Humans express: