The transport of α1A-adrenergic receptor with 33-nm step size in live cells

We used the technique of single particle tracking (SPT) with high tempo-spatial resolution to efficiently explore the route and mechanism for the transport of α1A-adrenergic receptor (α1A-AR) in real time in living cells. We found that the initial transport of α1A-AR in cells depended on actin filaments with the velocity of 0.2 μm/s and exhibited discrete 33-nm steps. It was noted that the step size, the rate constant, and the velocities were in accordance with the character of single myosin in vitro, implying that while transporting each endosome myosins did not work in the “tug-of-war” mode and that they did not adopt the strategy to boost up transporting speed by working coordinately. These results provided insight into the mechanism of GPCR transport in vivo.