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Structural differences between parent and mutant H-2K glycoproteins from two H-2K gene mutants: b6.c-h-2ba (Hzl) and
Abstract:
The H-2K glycoproteins from two mouse mutants B6.C-H-2ba (Hzl) and B6-H-2bd (M505) were isolated, and by tryptic peptide mapping techniques, were compared with each other and with the H-2K glycoprotein from the parent strain C57BL/6 (H-2b). The elution profile of the acid-soluble tryptic peptides from the H-2Kba glycoprotein showed that at least two to three arginine-labeled peptides and one lysine-labeled peptide were different from the H-2Kb product of the parent. These peptides were distinct from the soluble peptides which constitute the difference which was found between the H-2K products of H-2bd and the H-2b parent strains. The comparative peptide maps thus demonstrate small but significant primary structural differences among the H-2Kba, H-2Kbd, and H-2Kb glycoproteins. The findings are in agreement with the suggestion that alterations in the H-2K products from these two mutants are sufficient to permit their cells to stimulate each other and the parent cells in the mixed lymphocyte reaction (MLR) and to serve as target cells for the cell-mediated lymphocytotoxicity (CML) test. Because there is a significant reactivity in MLR and CML between H-2Kb, H-2Kba and H-2Kbd cells whereas there is no serologic reactivity, our findings are consistent with the notion there is a separation of the site(s) on the H-2 molecule having serologic reactivity and the site(s) involved in the MLR and CML reactivities.
Insights
Structural differences in mouse H-2K glycoproteins were identified between parent strains and mutants. These variations explain immune responses in mixed lymphocyte reactions and cell-mediated lymphocytotoxicity tests, despite lacking serologic reactivity.
Area of Science:
- Immunogenetics
- Molecular immunology
- Biochemistry
Background:
- The H-2K glycoproteins are crucial for immune responses in mice.
- Mouse mutants B6.C-H-2ba (Hzl) and B6-H-2bd (M505) exhibit distinct H-2K glycoproteins compared to the parent strain C57BL/6 (H-2b).
- Understanding these structural differences is key to deciphering immune recognition mechanisms.
Purpose of the Study:
- To compare the primary structures of H-2K glycoproteins from two mouse mutants (H-2Kba and H-2Kbd) with the parent strain (H-2Kb).
- To correlate observed structural variations with immune cell reactivity in mixed lymphocyte reactions (MLR) and cell-mediated lymphocytotoxicity (CML) assays.
- To investigate the relationship between serologic reactivity and immune cell stimulation sites on the H-2 molecule.
Main Methods:
- Isolation of H-2K glycoproteins from parent and mutant mouse strains.
- Tryptic peptide mapping of isolated H-2K glycoproteins.
- Analysis of elution profiles of acid-soluble tryptic peptides, focusing on arginine- and lysine-labeled peptides.
Main Results:
- Significant primary structural differences were identified in the H-2Kba and H-2Kbd glycoproteins compared to the H-2Kb parent.
- Specific arginine- and lysine-labeled tryptic peptides differed between the mutant and parent H-2K glycoproteins.
- These structural variations were distinct from those observed between the H-2Kbd mutant and the H-2Kb parent.
- The identified structural alterations align with the observed immune cell stimulations in MLR and CML assays.
Conclusions:
- Small but significant primary structural differences exist among H-2Kba, H-2Kbd, and H-2Kb glycoproteins.
- These structural changes in H-2K products are sufficient to mediate MLR and CML responses.
- The findings support a model where serologic reactivity sites are distinct from sites involved in MLR and CML immune cell interactions on the H-2 molecule.