| Autor: |
Robert M. Raphael, Ryan M. McGuire, Ramsey I. Kamar |
| Rok vydání: |
2009 |
| Předmět: |
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| Zdroj: |
Biophysical Journal. 96(3) |
| ISSN: |
0006-3495 |
| DOI: |
10.1016/j.bpj.2008.12.2780 |
| Popis: |
Outer hair cells (OHCs) possess the unique ability to undergo somatic length change in response to sound evoked alteration of transmembrane potential through a process termed electromotility. The acute sensitivity and frequency selectivity of mammalian hearing is dependent upon this process. Electromotility is driven by the transmembrane motor protein prestin which presumably undergoes a conformational change in response to transmembrane potential changes. Previous work demonstrates that prestin exists in multimeric states in the OHC and when exogenously expressed in mammalian cells. However the role that prestin oligomerization in its voltage-dependent motor function has not been defined. Towards this goal, we explore the role of prestin-prestin interactions by measuring fluorescence resonance energy transfer (FRET) as a function of transmembrane voltage in HEK293 cells co-expressing prestin-CFP and prestin-YFP fusion proteins. Our data show that prestin-prestin FRET efficiency decreases with depolarization over the operating range of voltages relevant to electromotility. Prestin-prestin FRET reaches saturation at depolarized voltages and preliminary data suggest the same at hyperpolarized voltages. Interestingly, when the voltage dependence of the FRET efficiency is modeled by a two state Boltzmann function, the valence of the fit closely agrees with the valence obtained from prestin nonlinear capacitance measurements. Our data suggest that voltage-dependent FRET is dependent on prestin-prestin interactions within or between oligomers. Whether these changes occur from voltage-dependent conformational changes in prestin that alter prestin oligomerization is currently being explored. (This work is supported by an NSF CAREER Award and NIH grant DC008134) |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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