1.A.7.1.2
ATP-gated cation channel (purinoceptor or ATP-neuroreceptor), P2X2.  His33 and Ser345 are proximal to each other across an intra-subunit interface, and the relative movement between the two TMSs is likely important for transmitting the action of ATP binding to the opening of the channel (Liang et al. 2013).  Two processes contribute to receptor desensitization, one, bath calcium-independent and the other, bath calcium-dependent, the latter being more important (Coddou et al. 2015).  ATP dissociation causes reduction in outer pore expansion compared to the ATP-bound state. Moreover, the inner and outer ends of adjacent pore-lining helices come closer during opening, likely through a hinge-bending motion (Habermacher et al. 2016). Hearing loss mutations alter the functional properties of human P2X2 receptor channels through more than one mechanism (George et al. 2019). Residues in TMSs of the P2X4 receptor that contribute to channel function and ethanol sensitivity have been identified (Popova et al. 2020). Self-assembly of mammalian cell membranes on bioelectronic devices with  P2X2 channel has been achieved (Liu et al. 2020). Lithocholic acid inhibits P2X2 and potentiates P2X4 receptor channel gating (Sivcev et al. 2020).