Structural studies of the H-2D products of the mouse mutant BALB/c-H-2Ddb and the parental strain BALB/cKh-H-2Dd.

The tryptic peptide profile characteristics of the H-2D glycoprotein, isolated by immunoprecipitation from the MHC mutant mouse strain BALB/c-H-2Ddb, were compared with those of the H-2D molecule from the parent strain BALB/cKh-H-2Dd. At each stage of purification these molecules exhibited identical biochemical properties and on peptide mapping we observed that the Ddb molecule showed no detectable peptide differences from the Dd molecule of the nonmutant parent. These data thus support the concept that the site of mutation in this mutant strain, although located in the D region of the MHC, is distinct from the gene coding for molecules bearing the H-2.4 private specificity.