Directed manipulation of membrane proteins by fluorescent magnetic nanoparticles

Abstract

The plasma membrane is the interface through which cells interact with their environment. Membrane proteins are embedded in the lipid bilayer of the plasma membrane and their function in this context is often linked to their specific location and dynamics within the membrane. However, few methods are available for nanoscale manipulation of membrane protein location at the single molecule level. Here, we report the use of fluorescent magnetic nanoparticles (FMNPs) to track membrane molecules and to manipulate their movement. FMNPs allow single-particle tracking (SPT) at 10 nm spatial and 5 ms temporal resolution, and using a magnetic needle, we pull membrane components laterally through the membrane with femtonewton-range forces. In this way, we successfully dragged lipid-anchored and transmembrane proteins over the surface of living cells. Doing so, we detected submembrane barriers and in combination with super-resolution microscopy could localize these barriers to the actin cytoskeleton. We present here a versatile approach to probe membrane processes in live cells via the magnetic control of membrane protein motion.