Small changes in the lateral organisation of components within the plasma membrane can cause dramatic effects on cellular function. As a result, the mobility of both transmembrane and single leaflet species has been the subject of intense study. A particularly appealing description of the cell membrane that has emerged in the past decade is that of the picket-fence model, based on high-speed single particle tracking of metallic nanoparticles on living cells. Nevertheless, there have been numerous reports that have questioned the validity of such approaches due to possible artefacts caused by the size of the label, the roughness of the membrane, or the precision of the imaging approach.Here, we used high-speed single particle tracking with interferometric scattering microscopy (iSCAT) with 1 nm spatial and 10 microsecond temporal accuracy of metallic nano particles as small as 20 nm to investigate the existence, role and mechanistic origin of time-dependent mobilities of membrane components in lipid bilayers. Using supported lipid bilayers as a model system, we demonstrate that surface-immobilization of GM1 on the lower leaflet induces anomalous subdiffusion of cholera toxin-bound GM1 in the upper leaflet. At the same time we show, by chemically modifying the lipid chain of GM1, that interleaflet coupling is a necessary element for the observed sub-diffusive behaviour. The observations are in excellent agreement with a simple barrier and valley model responsible for the onset of anomalous diffusion, in this case caused by pinned GM1 molecules on the lower leaflet. Our results demonstrate the validity of high-speed tracking using nanoparticle labels and present a general mechanism for communication across lipid bilayers in the absence of transmembrane components.