Identification of a protein sector in chicken MHC I.

<p>Statistical coupling analysis (SCA) was carried out on a multiple sequence alignment (MSA) of 141 sequences obtained from a similarity search querying the BF2*15∶01 heavy chain as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089657#pone.0089657-Smock1" target="_blank">[30]</a>. A) The degree of conservation of each heavy chain residue i in the MSA is computed as the Kullback-Leibler relative entropy D_i. Bigger bars indicate greater conservation. The 85 protein sector residues are in red, 6 polymorphic residues between BF2*15∶01 and BF2*19∶01 are in green and the 2 residues that are both polymorphic and part of the protein sector are in blue. All other residues are in grey. B) Protein sector residues are mapped as spheres onto a ribbon representation of the BF2*15∶01 structure. Colours as (A), with the peptide as yellow sticks. C) and D) Space filling representations of the MHC I heavy chain, coloured as (B). The contiguous network of residues forming a protein sector comprises of 31% of heavy chain residues.