title: Radioligand saturation binding for quantitative analysis of ligand-receptor interactions.
abstract: The reversible combination of a ligand with specific sites on the surface of a receptor is one of the most important processes in biochemistry. A classic equation with a useful simple graphical method was introduced to obtain the equilibrium constant,Kd, and the maximum density of receptors,Bmax. The entire125I-labeled ligand binding experiment includes three parts: the radiolabeling, cell saturation binding assays and the data analysis. The assay format described here is quick, simple, inexpensive, and effective, and provides a gold standard for the quantification of ligand-receptor interactions. Although the binding assays and quantitative analysis have not changed dramatically compared to the original methods, we integrate all the parts to calculate the parameters in one concise protocol and adjust many details according to our experience. In every step, several optional methods are provided to accommodate different experimental conditions. All these refinements make the whole protocol more understandable and user-friendly. In general, the experiment takes one person less than 8 h to complete, and the data analysis could be accomplished within 2 h.
authors.affiliation: Interdisciplinary Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China.
authors.forename: Chengyan
authors.initials: C
authors.lastname: Dong
authors.affiliation: Medical Isotopes Research Center and Department of Radiation Medicine, School of Basic Medical Sciences, Peking University, Beijing, 100191 China.
authors.forename: Zhaofei
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Interdisciplinary Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China ; Medical Isotopes Research Center and Department of Radiation Medicine, School of Basic Medical Sciences, Peking University, Beijing, 100191 China.
authors.forename: Fan
authors.initials: F
authors.lastname: Wang
keywords: Equilibrium constant; I-125 labeling; Maximum density of receptors; Radioligand; Saturation binding assays