Single-cell microinjection coupled to confocal microscopy to characterize nuclear membrane receptors in freshly...

Lipid bilayers, such as the plasma membrane and nuclear envelope, serve as effective cellular barriers to ions and macromolecules, thus allowing regulated access to subcellular compartments including the cytoplasm and nucleus, respectively. Of course, these barriers are semipermeable and a wide variety of proteins including transporters, ion exchangers, pumps, and ion channels are required to permit access as well as establish and maintain molecular and ionic gradients across membranes. However, some experimental designs, such as specifically targeting intracellular receptors, require the administration of membrane-impermeable molecules directly into live cells. The microinjection technique described in this chapter is an efficient, technically simple, and reliable approach that can be used to introduce macromolecules into intracellular compartments while maintaining the integrity of the plasma membrane itself.