KINETIC ANALYSIS OF TOXIN-RECEPTOR INTERACTIONS

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 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. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. 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.