کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1935706 | 1050673 | 2008 | 5 صفحه PDF | دانلود رایگان |
Functional Channelrhodopsin-2 (ChR2) overexpression of about 104 channels/μm2 in the plasma membrane of HEK293 cells was studied by patch-clamp and freeze-fracture electron microscopy. Simultaneous electrorotation measurements revealed that ChR2 expression was accompanied by a marked increase of the area-specific membrane capacitance (Cm). The Cm increase apparently resulted partly from an enlargement of the size and/or number of microvilli. This is suggested by a relatively large Cm of 1.15 ± 0.08 μF/cm2 in ChR2-expressing cells measured under isotonic conditions. This value was much higher than that of the control HEK293 cells (0.79 ± 0.02 μF/cm2). However, even after complete loss of microvilli under strong hypoosmolar conditions (100 mOsm), the ChR2-expressing cells still exhibited a significantly larger Cm (0.85 ± 0.07 μF/cm2) as compared to non-expressing control cells (0.70 ± 0.03 μF/cm2). Therefore, a second mechanism of capacitance increase may involve changes in the membrane permittivity and/or thickness due to the embedded ChR2 proteins.
Journal: Biochemical and Biophysical Research Communications - Volume 369, Issue 4, 16 May 2008, Pages 1022–1026