Mutation at amino acid position 133 of H-2Dd prevents beta 2m association and immune recognition but not surface expression.
The histocompatibility loss mutation H-2dm6 was derived from a mouse treated with the chemical mutagen ethylnitrosourea, and previous mapping studies implicated Dd as the affected locus. Southern blot analyses of DNA from H-2dm6 cells did not detect major deletions in the Ddm6 gene, suggesting that H-2dm6 was different from the previously characterized D region mutants H-2dm1 and H-2dm2. RNA blot analysis identified Ddm6 transcripts of appropriate size and a Ddm6 protein was immunoprecipitated from biosynthetically labeled H-2dm6 cells. Interestingly, the Ddm6 protein showed no beta 2m association and was only precipitated by a mAb to the alpha 3 domain. Furthermore, oligosaccharide maturation and low levels of surface expression of Ddm6 molecules were detected. However, the surface Ddm6 was nonfunctional as a target Ag in in vitro cytotoxicity assays, consistent with its original in vivo detection as a loss mutation. Sequence analyses of Ddm6 cDNA identified a single nucleotide base difference from wild-type, resulting in the substitution of a Trp to Arg at position 133. The significance of this substitution is discussed in the context of other class I expression variants.
Rubocki
R J
RJ
Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha 68105-1065.
Connolly
J M
JM
Hansen
T H
TH
Melvold
R W
RW
Kim
B S
BS
Hildebrand
W H
WH
Martinko
J
J
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002462:Cell Membrane / Q000378:metabolism; D003602:Cytotoxicity, Immunologic; D006183:H-2 Antigens / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D064532:Histocompatibility Antigen H-2D; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D009154:Mutation; D015345:Oligonucleotide Probes / Q000737:chemistry; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D011485:Protein Binding; D011487:Protein Conformation; D001613:beta 2-Microglobulin / Q000378:metabolism*
D006183:H-2 Antigens; D064532:Histocompatibility Antigen H-2D; D015345:Oligonucleotide Probes; D001613:beta 2-Microglobulin