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. 2009 Nov 19;285(5):3103–3113. doi: 10.1074/jbc.M109.053249

FIGURE 3.

FIGURE 3.

Cysteines of TMD 9 affect V½ of NLC. A, NLC curves constructed from mean fit parameters show that C381S and C395S prestin are depolarized compared with V½ of WT prestin (p < 0.01), but charge density and z are consistent with WT measures (see Figs. 4 and 5). B, V½ for all groups: WT, −78.6 ± 3.6 mV (n = 21); C52S, −67.3 ± 2.5 mV (n = 11); C124S, −77.8 ± 5.6 mV (n = 8); C192S/C196S, −68.3 ± 2.8 mV (n = 7); C260S, −76.5 ± 3.1 mV (n = 12); C381S, −57.2 ± 3.2 mV (n = 7); C395S, −6.06 ± 2.0 mV (n = 10); C415S, −84.6 ± 3.4 mV (n = 12); C679S, −67.4 ± 3.0 mV (n = 10). WT range is highlighted by a gray horizontal bar. C, the C395S mutant retains sensitivity to membrane cholesterol composition. Untreated C395S prestin has a V½ value that is 73 mV depolarized compared with WT prestin. Depletion of HEK membrane cholesterol by 10 mm methyl-β-cyclodextrin application for 15 or 30 min causes further depolarization of V½ to +63.0 ± 11.4 mV (n = 5) and +105.0 ± 3.8 mV (n = 4), respectively. The 69 mV (15-min depletion) and 111 mV (30-min depletion) shifts are statistically significant from V½ of untreated C395S and each other (p < 0.05). All V½ values are mean ± S.E.