Notelaers Kristof, Rocha Susana, Paesen Rik, Smisdom Nick, De Clercq Ben, Meier Jochen C, Rigo Jean-Michel, Hofkens Johan, Ameloot Marcel
Biochim Biophys Acta. 2014 Mar;1843(3):544-53. doi: 10.1016/j.bbamcr.2013.11.019.
Single particle tracking (SPT) of transmembrane receptors in the plasma membrane often reveals heterogeneous diffusion. A thorough interpretation of the displacements requires an extensive analysis suited for discrimination of different motion types present in the data. Here the diffusion pattern of the homomeric alpha3-containing glycine receptor (GlyR) is analyzed in the membrane of HEK 293 cells. More specifically, the influence of the alpha3 RNA splice variants alpha3K and alpha3L on lateral membrane diffusion of the receptor is revealed in detail. Using a combination of ensemble and local SPT analysis, free and anomalous diffusion parameters are determined. The GlyR alpha3 free diffusion coefficient is found to be 0.13 +/- 0.01 microm2/s and both receptor variants display confined motion. The confinement probability level and residence time are significantly elevated for the alpha3L variant compared to the alpha3K variant. Furthermore, for the alpha3L GlyR, the presence of directed motion was also established, with a velocity matching that of saltatory vesicular transport. These findings reveal that alpha3 GlyRs are prone to different types of anomalous diffusion and reinforce the role of RNA splicing in determining lateral membrane trafficking.
质膜中跨膜受体的单粒子追踪（SPT）常常揭示出异质性扩散。对位移进行全面解读需要进行广泛分析，以区分数据中存在的不同运动类型。在此，对含α3的同聚甘氨酸受体（GlyR）在HEK 293细胞膜中的扩散模式进行了分析。更具体地说，详细揭示了α3 RNA剪接变体α3K和α3L对受体侧向膜扩散的影响。通过结合总体和局部SPT分析，确定了自由扩散和异常扩散参数。发现GlyR α3的自由扩散系数为0.13±0.01μm²/s，且两种受体变体均表现出受限运动。与α3K变体相比，α3L变体的受限概率水平和停留时间显著升高。此外，对于α3L GlyR，还确定了存在定向运动，其速度与跳跃式囊泡运输的速度相匹配。这些发现表明α3 GlyRs易于出现不同类型的异常扩散，并强化了RNA剪接在决定侧向膜运输中的作用。
