Anomalous diffusion of single lipids at microsecond time scale in live cell plasma membrane
Yi-Hung Liao1*, Chih-Hsiang Lin1, Chia-Lung Hsieh1
1Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
* Presenter:Yi-Hung Liao,
Membrane lipids and proteins are revealed to move beyond simple Brownian motion in cell plasma membrane [1]. These non-Brownian motions (anomalous diffusion) are characterized by the sublinear scaling between the time and the mean squared displacement (MSD) of the moving molecule (subdiffusion) [2]. The dynamics of membrane molecules are implicated to result from membrane crowding, heterogeneities, and molecular interactions [3] because they generally require lateral motion so as to encounter reacting partners and initiate functions [4]. Therefore, understanding molecular dynamics in the plasma membrane is crucial to comprehending regulation of cellular events. Recently, the MSD of diffusing membrane molecules are found to scale sublinearly with time at sub- to milli- second timescales but linearly in microsecond regime [2]. Picket-fence model is proposed to explain the heterogeneity in dynamics across different timescales due to the meshes induced by membrane-anchoring cytoskeletons [5]. However, we argue that the membrane microdomains arising from the cholesterol-rich membranes could instigate anomalous diffusion as well inside membrane meshes. By using coherent brightfield microscopy [6] and monovalent gold nanoprobe [7], we provide first experimental evidence that at microsecond timescale the MSD of a single lipid molecule still scales sublinearly with time, i.e., single molecule experiences anomalous subdiffusion at the nanometer length scale in cell plasma membrane. Detailed analysis will be discussed.

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Keywords: single-particle tracking, plasma membrane, gold nanoparticle, subdiffusion