ABSTRACT
This chapter discusses the application of video imaging in combination with digital image analysis to the measurement of the dynamics of ligand-receptor complexes on the surfaces of cells. It focuses on the human low-density lipoprotein (LDL) receptor and a fluorescent analog ligand diI-LDL. The importance of the proper cellular-level processing of plasma LDL for cholesterol control in humans has been recognized for several years The methods for the production of the fluorescent analog diI-LDL and for the staining of cells with this ligand have been described in detail elsewhere. The chapter suggests that cytoskeletal activity modulates the mobility of the liganded-LDL receptor and that contractile tractions move receptors. Since the phycobiliprotein fluorescence is generated by a specific fluorophore structure instead of a statistical assembly of fluorophores, as in diI-LDL, the statistical spread of fluorescence is avoided.
