The motor protein prestin is a member of the SLC26 anion transporter family, and expressed in the lateral wall of OHCs. It is now widely recognized that prestin is required for mammalian cochlear amplification. Expression of prestin precedes the onset of hearing in mice and undergoes a functional maturation within the membrane coincident with the onset of hearing. We have developed several tetracycline‐inducible prestin expressing cell lines that duplicate prestins functional maturation in vivo. Thus, following induction there is an initial stage of increase in the charge carried by an individual motor (z) that accompanies a phase of slow growth in charge density. A plateau in z follows and is accompanied by rapid increase in charge density. The latter strongly correlates with an increasing ratio between an apparently larger and smaller monomer of prestin, suggesting that the latter exerts a dominant negative effect on function. Through the experimental period there is a progressive shift in the voltage of peak capacitance, similar to that observed in developing OHCs. Finally, we observed a non‐selective ionic current after induction, the size of which correlated with charge density.
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