CELLULAR AND STRUCTURAL STUDIES OF MYELOMA MUTANTS

我的研究兴趣集中在检查MPC 11的几个变体 合成改变的免疫球蛋白的产生IgG 2b的小鼠骨髓瘤细胞系 沉重的锁链 一些改变的重链比亲本短， 分子量为50，000或40，000，而亲本分子量为55，000; 其他具有血清学、肽和装配特征的新亚类， IgG 2a。 后者特别有趣，因为它们代表了 先前沉默的恒定区基因的表达。 我们正在研究 这些变体彼此之间，与亲本MPC 11之间， 以及MOPC 173和已知序列的IgG 2a蛋白。 我们已经证明， 几种IgG 2a变体蛋白保留了亲本独特型，但不同于 彼此通过肽图谱、电荷和组装参数。 这些相同 参数使我们能够对变体进行分组。 分析技术 木瓜蛋白酶消化产物如免疫电泳、溴化氰SDS-PAGE 片段和比较肽图，以及部分初级肽图 结构分析表明，一种变体蛋白的Fc完全是 γ 2a样，而第二个的Fc是γ 2b-γ 2a杂合体。 这些和其他变异的特征为我们提供了定位小鼠的工具 重链同种异型决定簇，以探测 巨噬细胞Fc受体的相互作用，并定义分子事件， 分泌物 这些发现表明，一些变异似乎使一个 重组重链和γ 2a和γ 2b恒定区具有 广泛的同源性提出了基因重排是否 发生在这些细胞中。 我们将制备限制酶片段， 亲本和变异细胞的基因组DNA，并通过与 亚类特异性cDNA探针，看看杂交模式是否不同。 此外，我们将探讨诱变剂在这些细胞中的作用问题。 通过询问在用ICR-191或美法仑等药物治疗后， 重组增强，或发生任何严重的染色体异常。

My research interests focus on examining several variants of the MPC 11 IgG2b-producing mouse myeloma cell lines which synthesize altered immunoglobulin heavy chains. Some altered heavy chains are shorter than the parent, having molecular weights of 50,000 or 40,000 compared to the parental size of 55,000; others have serological, peptide and assembly characteristics of a new subclass, IgG2a. The latter are especially interesting because they represent the expression of a previously silent constant region gene. We are studying the structural relationships of these variants to each other, to the parental MPC11, and to MOPC 173, and IgG2a protein of known sequence. We have shown that the several IgG2a variant proteins retain the parental idiotype, yet differ from each other by peptide maps, charge and assembly parameters. These same parameters have enabled us to subgroup the variants. Analytical techniques of papain digestion products such as immunoelectrophoresis, SDS-PAGE of CNBr fragments, and comparative peptide maps, in addition to partial primary structural analysis have shown that the Fc of one variant protein is entirely gamma2a-like while the Fc of a second is a gammma2b-gamma 2a hybrid. Characterization of these and other variants gives us tools to localize mouse heavy chain allotypic determinants, to probe the molecular requirements for macrophage Fc receptor interactions, and to define molecular events in secretion. The findings that indicate that some variants seem to make a recombinant heavy chain and that gamma2a and gamma2b constant regions have extensive homology raise the question of whether gene rearrangements are occurring in these cells. We will prepare restriction enzyme fragments from genomic DNA of parent and variant cells and examine them by hybridization with subclass-specific cDNA probes to see if the patterns of hybridization differ. In addition, we will approach the question of the action of mutagens in these cells by asking whether after treatment with drugs such as ICR-191 or Melphalan, recombination is enhanced, or any gross chromosomal abnormalities are occurring.