Binding of alanine‐substituted peptides to the MHC class I protein, Kd

Publisher Website
Google Scholar
Abstract
Peptides eluted from the native MHC class I molecule, K d , are generally nonamers that display a strong preference for Tyr in position 2. We investigated the molecular basis for this ‘consensus motif’ by synthesizing a virally derived peptide, NP 147–155, that is known to be presented by K d on living cells, and peptide variants of NP 147–155 in which the amino acids in the different positions were sequentially replaced by Ala. All of the peptides bound to purified K d molecules in vitro with high affinity, except for the peptide in which Tyr 2 was replaced by Ala, for which the affinity for K d decreased at least 100-fold. These results confirm the interpretation of the in vivo studies; namely, that Tyr 2 is a critical anchor residue for binding to K d .