KINETIC ANALYSIS OF TOXIN-RECEPTOR INTERACTIONS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 许多关键的生物反应发生在双层膜表面上。一类重要的此类反应是可溶性配体与其细胞表面受体之间的相互作用。配体-受体的相互作用可以是单价的，就像小肽配体的情况一样，可以是双价的，就像许多大的多肽激素和抗体一样，或者是更高的价态。后一类是许多细菌毒素与它们的细胞表面受体之间的相互作用。例如，霍乱毒素进入哺乳动物细胞是通过五聚体B亚单位与细胞膜上的神经节苷脂GM1结合而实现的。这种相互作用的显著特征包括单个B亚基与GM1的碳水化合物部分之间的低亲和力单价相互作用，五聚体B亚基与几个膜结合的GM1分子之间的高亲和力多价相互作用，以及GM1分子在双层膜内的横向迁移性。我们最近将我们对固定化双催化器的研究扩展到了活细胞中毒素处理的研究。利用动力学和温度控制的流式细胞术，我们正在研究活细胞中各种内化途径的速率和能力。这些结果正被用于建立和测试细胞内配体处理的模型。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Many critical biological reactions occur in or on bilayer membrane surfaces. An important class of such reactions is the interactions between soluble ligands and their cell-surface receptors. Ligand-receptor interactions may be monovalent, as is the case for small peptide ligands, bivalent, as for many large peptide hormones and antibodies, or of even higher valencies. In the latter class are the interactions between many bacterial toxins and their cell-surface receptors. Cholera toxin entry into mammalian cells, for example is mediated by binding of the pentameric B subunit to ganglioside Gm1 in the cell membrane. Notable features of this interaction include a low affinity monovalent interaction between individual B subunits and the carbohydrate moiety of Gm1, a high affinity multivalent interaction between pentameric B subunit with several membrane-bound Gm1 molecules, and the lateral mobility of the Gm1 molecule within the bilayer membrane. We have recently extended our studies on immobilized bialyers to the study of toxin processing in live cells. Using kinetic and temperature controlled flow cytometry, we are investigating the rates and capacities of various internalization pathways in live cells. These results are being used to build and test models of intracellular ligand processing.