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Prestin is a protein that is critical to sensitive hearing in mammals. It is encoded by the ''SLC26A5'' (solute carrier anion transporter family 26, member 5) gene.〔(【引用サイトリンク】 url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=375611 )〕 Prestin is the motor protein of the outer hair cells of the inner ear of the mammalian cochlea.〔It is highly expressed in the outer hair cells, and is not expressed in the nonmotile inner hair cells. Immunolocalization shows prestin is expressed in the lateral plasma membrane of the outer hair cells, the region where (electromotility ) occurs. The expression pattern correlates with the appearance of outer hair cell electromotility. == Function == Prestin is essential in auditory processing. It is specifically expressed in the lateral membrane of outer hair cells (OHCs) of the cochlea. There is no significant difference between prestin density in high-frequency and low-frequency regions of the cochlea in fully developed mammals. There is good evidence that prestin has undergone adaptive evolution in mammals associated with acquisition of high frequency hearing in mammals. The prestin protein shows several parallel amino acid replacements in bats and dolphins that have independently evolved ultrasonic hearing and echolocation, and it represents a rare case of convergent evolution at the sequence level. Prestin (mol. wt. 80 kDa) is a member of a distinct family of anion transporters, SLC26. Members of this family are structurally well conserved and can mediate the electroneutral exchange of chloride and carbonate across the plasma membrane of mammalian cells, two anions found to be essential for outer hair cell motility. Unlike the classical, enzymatically driven motors, this new type of motor is based on direct voltage-to-displacement conversion and acts several orders of magnitude faster than other cellular motor proteins. A targeted gene disruption strategy of prestin showed a >100-fold (or 40 dB) loss of auditory sensitivity. Prestin is a transmembrane protein that mechanically contracts and elongates leading to electromotility of outer hair cells (OHC). Electromotility is the driving force behind the somatic motor of the cochlear amplifier, which is a mammalian evolution that increases sensitivity to incoming sound wave frequencies and, thus, amplifies the signal. Previous research has suggested that this modulation takes place via an extrinsic voltage-sensor (partial anion transporter model), whereby chloride binds to the intracellular side of prestin and enters a defunct transporter, causing prestin elongation. However, there is new evidence that prestin acts through an intrinsic voltage-sensor (IVS) in which intracellular chloride binds allosterically to prestin to modify shape. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Prestin」の詳細全文を読む スポンサード リンク
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