Structural diversity of human class II histocompatibility molecules induced by peptide ligands

SDS-PAGE analyses of stable HLA-DR1 complexes indicate that the binding of T cell epitopes can lead to multiple conformational variants. Whereas short T epitopes (< 14-mer) induce complexes with apparent MW ranging from 47 to 57 kDa, longer peptides form generally high mobility complexes (44-45 kDa) , The generation of HLA-DR1 conformational variants appears dependent on co re peptide residues fitting inside the groove but can additionally be attri buted to the presence of Nand C-terminal flanking residues (PFRs) acting as a complementary mechanism, These PFRs can jointly affect major histocompat ibility complex class II conformation and stability, supporting the existen ce of alternative contacts at a distance from the classical binding site. ( C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.