In the inner ear, hair cells detect not only sounds but also acceleration with their mechanotransduction apparatus. In this study, I demonstrate that transduction and adaptation require phosphatidylinositol-4,5-bisphosphate (PIP
2) for normal kinetics. PIP
2 has a striking distribution in hair cells, being excluded from the basal region of hair bundles and apical surfaces of bullfrog saccular hair cells. The depletion of PIP
2 by the inhibition of phosphatidylinositol 4-kinase or sequestration by an aminoglycoside reduces the rate of fast and slow adaptation, and also causes a loss in transduction currents, suggesting that PIP
2 plays an essential role in hair cell adaptation and transduction.
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