Single particle tracking of acyl carrier protein (ACP)-tagged TrkA receptors in PC12nnr5 cells.

There is a wide interest in studying the membrane mobility of Nerve Growth Factor (NGF) tropomyosin receptor kinase A (TrkA) at the single molecule level, in order to elucidate its diverse signaling responses related to different receptor functions. Here we present an experimental strategy based on the acyl carrier protein (ACP) tag in order to study the dynamics of the high-affinity NGF receptor TrkA in the membrane of PC12nnr5 cells. We present a single-particle tracking (SPT) study using highly photostable semiconductor quantum dots (Qdots) conjugated to ACP-tagged TrkA receptors. We demonstrate that ACP-TrkA shows biochemical and biological properties identical to those of its unmodified counterpart and that single receptor molecules in living cells display distinct diffusive regimes and a highly heterogeneous dynamics.