2.A.53.2.5
Prestin, the outer hair cell voltage-sensitive motor protein (voltage sensitivity depends on intracellular Cl^- and HCO₃^- which may bind to prestin). Prestin transports anions including formate and oxalate; transport and voltage-sensing capabilities are independent functions of the same protein (Bai et al., 2009). Prestin-mediated electromotility is a dual-step process: transport of anions by an alternate access cycle, followed by an anion-dependent transition generating electromotility (Schaechinger et al., 2011; McGuire et al., 2011).  A three-dimensional molecular dynamics model of prestin predicted that it contains eight transmembrane spanning segments and two helical re-entry loops. Tyrosyl residues recognize anions, with residues Y367, Y486, Y501 and Y508 contributing to anion binding through anion-pi interactions. Such interactions, sensitive to voltage and mechanical stimulation, confer a capability to perform electromechanical and mechanoelectric conversions (Lovas et al. 2015).