Length distribution of amino terminal PFRs for MHC-II binding and non-binding peptides. All peptide data for the three alleles in the AntiJen and IEDB data sets are included in the figure. Binding peptides have an affinity stronger than 500 nM. The PFR is defined as the residues flanking the peptide-binding core as determined by the SMM-align method.
Nielsen et al. BMC Bioinformatics 2007 8:238 doi:10.1186/1471-2105-8-238