title: A single amino acid substitution in the alpha 3 domain of an H-2 class I molecule abrogates reactivity with CTL.
abstract: We previously described a somatic cell expressing a variant H-2Dd molecule that did not serve as a target for alloreactive anti-Dd CTL. The mutant cell line had been isolated by its failure to express a serological epitope present on the H-2Dd alpha 3 domain. In the present study the alpha 3 domain of the Dd molecule of this somatic cell variant was sequenced and a single nucleotide change resulting in a glutamic acid to lysine substitution at residue 227 was identified. This change was reproduced in the cloned H-2Dd gene by oligonucleotide-directed mutagenesis. Cells transfected with this mutant gene were not killed by anti-H-2Dd CTL. Because previous studies using hybrid H-2 class I molecules had established that the alpha 3 domain does not express allele-specific determinants recognized by CTL, our results raise the possibility that residues in the alpha 3 domain of H-2 class I molecules are critical for CTL recognition and constitute a conserved (or monomorphic) determinant recognized by CTL.
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D000818:Animals; D002460:Cell Line; D004247:DNA / Q000032:analysis; D006183:H-2 Antigens / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D064532:Histocompatibility Antigen H-2D; D007376:Interleukin-2 / Q000096:biosynthesis; D051379:Mice; D009154:Mutation; D013329:Structure-Activity Relationship; D013602:T-Lymphocytes, Cytotoxic / Q000378:metabolism; D014162:Transfection
chemical_list: D000596:Amino Acids; D006183:H-2 Antigens; D064532:Histocompatibility Antigen H-2D; D007376:Interleukin-2; D004247:DNA