Class II major histocompatibility complex (MHCII) molecules present antigens to CD4(+) T cells. In addition to the most commonly studied human MHCII isotype, HLA-DR, whose beta chain is encoded by the HLA-DRB1 locus, several other isotypes that use the same alpha chain but have beta chains encoded by other genes ...
Class II major histocompatibility complex (MHCII) molecules present antigens to CD4(+) T cells. In addition to the most commonly studied human MHCII isotype, HLA-DR, whose beta chain is encoded by the HLA-DRB1 locus, several other isotypes that use the same alpha chain but have beta chains encoded by other genes. These other DR molecules also are expressed in antigen-presenting cells and are known to participate in peptide presentation to T cells and to be recognized as alloantigens by other T cells. Like some of the HLA-DRB1 alleles, several of these alternate DR molecules have been associated with specific autoimmune diseases and T cell hypersensitivity. Here we present the structure of an HLA-DR molecule (DR52c) containing one of these alternate beta chains (HLA-DRB3*0301) bound to a self-peptide derived from the Tu elongation factor. The molecule shares structurally conserved elements with other MHC class II molecules but has some unique features in the peptide-binding groove. Comparison of the three major HLA-DBR3 alleles (DR52a, b, and c) suggests that they were derived from one another by recombination events that scrambled the four major peptide-binding pockets at peptide positions 1, 4, 6, and 9 but left virtually no polymorphisms elsewhere in the molecules.
Organizational Affiliation:
Integrated Department of Immunology, Howard Hughes Medical Institute, National Jewish Medical and Research Center, Denver, CO 80206, USA.
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