The outer hair cells of the mammalian cochlea are specialized cells and function early on in the hearing process. Recently, prestin, the motor protein responsible for the electromotility of outer hair cells, has been identified and cloned. Oliver et al. found that the unusual voltage sensitivity of this protein is not intrinsic but depends on the presence of intracellular anions, such as bicarbonate and chloride, which behave like extrinsic voltage sensors. In binding to the motor protein, they trigger the structural rearrangements in the molecule that underlie outer hair cell electromotility.
D. Oliver, D. Z. Z. He, N. Klöcker, J. Ludwig, U. Schulte, S. Waldegger, J. P. Ruppersberg, P. Dallos, B. Fakler, Intracellular anions as the voltage sensor of prestin, the outer hair cell motor protein. Science 292, 2340-2343 (2001). [Abstract] [Full Text]