Radioligand Binding in Intact Cells

Radioligand binding to plasma membranes or complete cell homogenates has been widely used to characterize the binding interactions between a large number of receptors and ligands (see Chapters 1 –3 ). These experiments are generally performed under conditions that optimize the data obtained but are usually nonphysiological. It is difficult to compare the binding affinity obtained for a radioligand to cell membranes, in a low ionic strength buffer that contains no divalent cations, with functional assays performed under near-physiological conditions. However, there are a number of complicating factors that must be considered when using intact cells. The aim of this chapter is to describe the additional factors that must be taken into consideration when measuring radioligand binding in intact cells.