title: A transposable epitope of HLA-B7, B40 molecules.
abstract: The monoclonal antibody MB40.2 defines a novel subtype of HLA-B40 that is expressed by the Sweig cell line. This molecule, called HLA-B40, lacks an antigenic determinant that is common to HLA-B7 and the HLA-Bw60 subtype of HLA-B40. Genes encoding HLA-B40 and HLA-Bw60 have now been isolated and the amino acid sequences of these proteins compared with other HLA-B locus molecules. These results show that HLA-B40 is a unique protein which differs from HLA-Bw60 by eight amino acid substitutions. Comparison of the sequences for HLA-B40, -Bw60, and -B7 localizes the MB40.2 epitope to a cluster of three substitutions at positions 177, 178, and 180 at the end of the alpha 2 domain. Gene conversion or reciprocal recombination are postulated to have transferred this cluster of substitutions, and their associated epitope, during the evolution of HLA-B locus genes. The epitope may consist of an alpha helical segment which is exclusively found on MB40.2-positive molecules.
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D001402:B-Lymphocytes / Q000276:immunology; D002460:Cell Line; D004251:DNA Transposable Elements; D000939:Epitopes / Q000032:analysis*; D005796:Genes; D006680:HLA Antigens / Q000235:genetics*; D015235:HLA-B Antigens; D059947:HLA-B40 Antigen; D015793:HLA-B7 Antigen; D006801:Humans; D011110:Polymorphism, Genetic
chemical_list: D000911:Antibodies, Monoclonal; D004251:DNA Transposable Elements; D000939:Epitopes; D006680:HLA Antigens; D015235:HLA-B Antigens; D059947:HLA-B40 Antigen; D015793:HLA-B7 Antigen