Excitation of fluorescent dyes inactivates the outer hair cell integral membrane motor protein prestin and betrays its lateral mobility.
The outer hair cell motor protein, prestin, which resides exclusively in the cell's lateral membrane, underlies the mammal's exquisite sense of hearing. Here we show that photoexposure of the commonly used dyes Lucifer yellow, 6-carboxy-fluorescein, and 4-(2-[6-(dioctylamino)-2-naphthalenyl]ethenyl)-1-(3-sulfopropyl)-pyridinium (di-8-ANEPPS), that are in contact with the cell's lateral membrane can photo-inactivate the motor irreversibly, as evidenced by reduction in prestin's gating charge displacement or non-linear capacitance. Furthermore, utilizing restricted fiber optic illumination of the lateral membrane, we show that whole-cell, non-linear capacitance is depleted beyond that expected for an immobile population in the exposed area. These data indicate that lateral diffusion of prestin occurs within the cell's lateral plasma membrane.
Santos-Sacchi
Joseph
J
Surgery (Otolaryngology) and Neurobiology, BML 244, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA. joseph.santos-sacchi@yale.edu
Zhao
Hong-Bo
HB
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D005452:Fluoresceins / Q000494:pharmacology; D036681:Fluorescence Recovery After Photobleaching; D005456:Fluorescent Dyes / Q000494:pharmacology*; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000378:metabolism*; D007546:Isoquinolines / Q000494:pharmacology*; D008956:Models, Chemical; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000378:metabolism; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D011726:Pyridinium Compounds / Q000494:pharmacology
C089669:1-(3-sulfonatopropyl)-4-(beta-(2-(di-n-octylamino)-6-naphthyl)vinyl)pyridinium betaine; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007546:Isoquinolines; D020409:Molecular Motor Proteins; C498722:Pres protein, Cavia porcellus; D011506:Proteins; D011726:Pyridinium Compounds; C024098:6-carboxyfluorescein; C017475:lucifer yellow