Tension sensitivity of prestin: comparison with the membrane motor in outer hair cells.

The membrane motor in outer hair cells undergoes conformational transitions involving charge displacement of approximately 0.8 e across the membrane and changes of approximately 4 nm(2) in its membrane area. Previous reports have established that the charge transfer in the membrane motor and that in prestin, a membrane protein in the plasma membrane of outer hair cells, are approximately equal. Here, we determine the membrane area changes based on its sensitivity to membrane tension. We found that prestin does undergo area changes and that the magnitude is approximately 1 nm(2), smaller than the value 4 nm(2) for outer hair cell motor. This result confirms that prestin is a protein that functions as a membrane motor based on piezoelectricity. The discrepancy in the magnitude could suggest a prestin-containing complex in outer hair cells.