This was initially demonstrated for the Shaker channel (Banghart et al., 2004). Because of the high degree of conservation of the pore region click here of potassium channels, photoblock by MAQ was readily generalized to a diverse set of additional potassium channels, including members of two subfamilies of classical voltage-gated channels (Kv1.3 and Kv3.1), the M-current channel (Kv7.2), and one of the Ca2+-activated K+ channels that generates the long-lasting action potential

afterhyperpolarization (SK2) (Fortin et al., 2011). A major reason for the ease of transferring the strategy to other channels is that the high effective concentration of the quaternary ammonium ligand near the pore in the blocking state assures efficient block, even if the affinity for the blocker is low. Moreover, the energy of the azobenzene isomerization is so large that it ensures efficient dissociation in the nonblocking

state even if the affinity for block by quaternary ammonium ions is high. In the present study, photoblock with MAQ was successfully applied for the first time to a 2P potassium channel, the TREK1 channel, despite its low affinity for the most broadly used quaternary ammonium blocker, tetraethylammonium (Noël et al., 2011). As further evidence of the generalizability of the approach, we also adapted MAQ photoblock to an additional 2P potassium channel target: TASK3. Based on the success of MAQ so far, it seems likely that it will work SP600125 chemical structure on the majority of potassium channels. Since the PCS approach requires that the photocontrol work when only a subset of subunits (the PCS)

carry the PTL, but the wild-type subunits do not, the approach is particularly well suited to photoblock of an enzyme active site or channel pore, because block can usually be accomplished by a single ligand, as is the case for quaternary ammonium block of potassium channels. However, the system should also work in cases where the protein complex is composed of more than one type of subunit, such as in the NMDA receptor. In this case the subunit that controls function, the NR2 subunit, would serve as the PCS and be controlled allosterically by a PTL attached to a cysteine introduced into the ligand binding domain. The second condition that must be fulfilled for the PCS strategy to work is that the only PCS subunits to arrive at the plasma membrane (-)-p-Bromotetramisole Oxalate are ones that have coassembled with native subunits. To achieve this either the subunit must naturally require coassembly with a distinct partner to traffic to the surface or mutation(s) need to be introduced into the PCS that result in its intracellular retention except in cells that express the wild-type subunit. In addition to the C-terminal deletion of TREK1 that we employed here, several other methods have been reported that provide for this kind of control. A variety of forward trafficking signals that drive localization to the plasma membrane have been identified and these can be disabled by mutation.