Biophysics Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, Maryland, USA.
Biophys J. 2010 Jun 16;98(12):2831-8. doi: 10.1016/j.bpj.2010.03.034.
Prestin is the membrane protein in outer hair cells that harnesses electrical energy by changing its membrane area in response to changes in the membrane potential. To examine the effect of membrane thickness on this protein, phosphatidylcholine (PC) with various acyl-chain lengths were incorporated into the plasma membrane by using gamma-cyclodextrin. Incorporation of short chain PCs increased the linear capacitance and positively shifted the voltage dependence of prestin, up to 120 mV, in cultured cells. PCs with long acyl chains had the opposite effects. Because the linear capacitance is inversely related to the membrane thickness, these voltage shifts are attributable to membrane thickness. The corresponding voltage shifts of electromotility were observed in outer hair cells. These results demonstrate that electromotility is extremely sensitive to the thickness of the plasma membrane, presumably involving hydrophobic mismatch. These observations indicate that the extended state of the motor molecule, which is associated with the elongation of outer hair cells, has a conformation with a shorter hydrophobic height in the lipid bilayer.
Prestin 是外毛细胞中的膜蛋白，它通过响应膜电位的变化改变其膜面积来利用电能。为了研究膜厚度对这种蛋白的影响，使用γ-环糊精将具有不同酰链长度的磷脂酰胆碱 (PC) 掺入到质膜中。短链 PC 的掺入增加了线性电容，并将 prestin 的电压依赖性正向移动，最高可达 120 mV，在培养细胞中。长链酰基 PC 具有相反的作用。由于线性电容与膜厚度成反比，这些电压移动归因于膜厚度。在外毛细胞中观察到相应的运动电活动的电压移动。这些结果表明，运动电活动对外质膜的厚度极其敏感，可能涉及疏水性失配。这些观察表明，与外毛细胞伸长相关的运动分子的延伸状态在脂质双层中具有较短的疏水性高度的构象。
