Changes

==Antigen/MHC Interaction==

==Antigen/MHC Interaction==

* The MHC molecules do not recognise specific amino acid sequences of antigens

MHC molecules do not recognise specific amino acid sequences of antigens, rather they recognise particular motifs of amino acids. The association of any MHC allele with a peptide may be determined by the presence of as few as two amino acids, however these determinants must be present in a particular array. The actual identity of the amino acids in not important for MHC binding but the physical and chemical characteristics of the amino acid are vitally important.

** Instead, they recognise particular motifs of amino acids

 

* The association of any MHC allele with a peptide may be determined by the presence of as few as two amino acids

Interactions of individual amino acids at the head and tail of the peptide-binding groove control the binding of peptides. The amino acids are mainly positioned at the floor of the antigen-binding groove, or within the helices facing into the groove. MHC amino acids associate with the amino acids near the ends of the peptides and the intervening stretch of peptide folds into a helix within the groove.

** However, these determinants must be present within a particular array

 

* The actual identity of the amino acids in not important for MHC binding

MHC molecules have the capacity to bind to trillions of different peptides. They adopt a flexible, floppy conformation until peptide binding when the molecules fold around the peptide to increase the stability of the complex. A small number of anchor residues then tether the peptide allowing different sequences between anchors and different lengths of peptides to bind.

** Instead, the physical and chemical characteristics of the amino acid are vital

* Interactions of individual amino acids at the head and tail of the peptide-binding groove control the binding of peptides

** Are mainly positioned at the floor of the antigen-binding groove, or within the helices facing into the groove

** These MHC amino acids associate with amino acids near the ends of the peptides

*** The intervening stretch of peptide folds into a helix within the groove

*MHC molecules have the capacity to bind to trillions of different peptides

**Adopt a flexible '''floppy''' conformation until a peptide binds

**Folds around the peptide to increase stability of the complex

**Uses a small number of anchor residues to tether the peptide allowing different sequences between anchors and different lengths of peptides to bind

==TCR-MHC Interaction==

==TCR-MHC Interaction==