Single molecule diffusion analysis on cellular nanotubules: Implications on plasma membrane structure below the diffraction limit

Cells are frequently interconnected by tunneling nanotubules, recently discovered cylindrical structures which facilitate material exchange. We employed here single molecule fluorescence microscopy to study the diffusion of the glycosylphosphatidylinositol-protein CD59 in the plasma membrane of tunneling nanotubules in living cells at subwavelength resolution. Our study provides the nanotubule radius in vivo, yielding a surprisingly narrow size distribution (⁠$7nm$ standard deviation) around a mean value of $65nm$⁠. Moreover, by separating longitudinal and transverse mobilities, we find isotropic diffusion behavior.