McKean D J, Melvold R W, David C
Immunogenetics. 1981;14(1-2):41-51. doi: 10.1007/BF00344298.
Previous studies of the B5.C-H-2 bm12 (bm12) strain have demonstrated the presence of a mutation localized to the I-A subregion of the mouse H-2 major histocompatibility complex. This mutation has been shown to be responsible for defects in Ir-gene function in Ia and MLR determinants. A comparison of the molecular size of the bm12 mutant and the parental B6 Ia-antigen component polypeptides failed to demonstrate any differences in the alpha and beta polypeptides. Thus, no major structural additions for deletions are present in the Ia alpha and beta chain polypeptide or carbohydrate structure. A significant decrease in the amount of invariant (31K) polypeptide was, however, consistently observed in the bm12 Ia antigen preparations. Tryptic peptide comparisons of 14C B6 and 3H bm 12 alpha and beta polypeptides demonstrated a limited number of peptide differences in the bm 12 beta polypeptide but none in the bm12 alpha polypeptide. The significance of these biochemical mutations and altered biological phenomena are discussed in relation to a model of the immunological interaction sites on Ia antigens.
先前对B5.C-H-2bm12（bm12）品系的研究表明，在小鼠H-2主要组织相容性复合体的I-A亚区存在一个突变。已证明该突变是Ia和混合淋巴细胞反应（MLR）决定簇中Ir基因功能缺陷的原因。对bm12突变体和亲本B6 Ia抗原成分多肽的分子大小进行比较，未发现α和β多肽有任何差异。因此，Iaα和β链多肽或碳水化合物结构中不存在主要的结构增加或缺失。然而，在bm12 Ia抗原制剂中始终观察到恒定（31K）多肽的量显著减少。对14C B6和3H bm12α和β多肽的胰蛋白酶肽段比较表明，bm12β多肽中存在有限数量的肽段差异，而bm12α多肽中没有。结合Ia抗原上免疫相互作用位点的模型，讨论了这些生化突变和改变的生物学现象的意义。
