Interaction among B cell, T cell, & macrophage

Aaron J. Mackey ajmackey at
Thu Sep 14 22:09:09 EST 1995

In article <marten.schneider-1409951241480001 at>,
Mårten Schneider <marten.schneider at> wrote:
>Also, it is important to consider that the TCR does not only bind to the
>peptide presented by MHC. In fact it binds to the 3-D product made up by
>MHC+peptide and the majority of what it binds is the MHC. Most of the
>amino acids of the peptide will be hidden in the peptide binding groove of
>the MHC and only a few amino acids will be exposed to the TCR. Note also
>that the 3-D structure of the MHC alters depending on which peptide it

Peptide binding in the MHC groove is mediated by anchor residues common 
among all the peptides which bind to a given MHC molecule.  The most 
often (so far) crystallized MHC-peptide complexes have been with a human 
class I MHC molecule bound to a single peptide (allowing the x-ray 
determination of the entire structure including the peptide).  So, if you 
take a look at these structures, which all have the same MHC bound to 
different peptides (which share the anchor residue motif), while the 
surface or epitope of the peptide is certainly different, the 
conformational change induced by the peptide on the MHC which binds it is 
minimal between different peptides.  In other words, this last statement 
is probably not true, the TcR recognizes the same MHC determinants, 
regardless of the peptide bound.

Aaron Mackey
Washington University in St. Louis
ajmackey at

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