TY - JOUR
T1 - Prestin forms oligomer with four mechanically independent subunits
AU - Wang, Xiang
AU - Yang, Shiming
AU - Jia, Shuping
AU - He, David Z.Z.
N1 - Funding Information:
This work was supported by NIH grant R01 DC004696 from the NIDCD to D.H. and by National Natural Science Foundation of China grant number 30628030 to SY and DH. We thank Drs. Peter Dallos, Stephen Neely, Yi-Wen Liu, and Ben Currall for many helpful discussions. The project described was, in part, supported by grant number G20RR024001 from the National Center for Research Resources . The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center for Research Resources or the NIH.
PY - 2010/5/28
Y1 - 2010/5/28
N2 - Prestin is the motor protein of cochlear outer hair cells (OHCs) with the unique capability of performing direct, rapid, and reciprocal electromechanical conversion. Prestin consists of 744 amino acids with a molecular mass of ∼ 81.4 kDa. The predicted membrane topology and molecular mass of a single prestin molecule appear inadequate to account for the size of intramembrane particles (IMPs) expressed in the OHC membrane. Although recent biochemical evidence suggests that prestin forms homo-oligomers, most likely as a tetramer, the oligomeric structure of prestin in OHCs remains unclear. We obtained the charge density of prestin in the gerbil OHCs by measuring their nonlinear capacitance (NLC). The average charge density (22,608 μm-2) measured was four times the average IMP density (5686 μm-2) reported in the freeze-fracture study. This suggests that each IMP contains four prestin molecules, based on the general notion that each prestin transfers a single elementary charge. We subsequently compared the voltage dependency and the values of slope factor of NLC and somatic motility simultaneously measured from the same OHCs to determine whether NLC and motility are fully coupled and how prestin subunits function within the tetramer. We showed that the voltage dependency and slope factors of NLC and motility were not statistically different, suggesting that NLC and motility are fully coupled. The fact that the slope factor is the same between NLC and motility suggests that each prestin monomer in the tetramer is in parallel, each interacting independently with cytoplasmic or other partners to facilitate the mechanical response.
AB - Prestin is the motor protein of cochlear outer hair cells (OHCs) with the unique capability of performing direct, rapid, and reciprocal electromechanical conversion. Prestin consists of 744 amino acids with a molecular mass of ∼ 81.4 kDa. The predicted membrane topology and molecular mass of a single prestin molecule appear inadequate to account for the size of intramembrane particles (IMPs) expressed in the OHC membrane. Although recent biochemical evidence suggests that prestin forms homo-oligomers, most likely as a tetramer, the oligomeric structure of prestin in OHCs remains unclear. We obtained the charge density of prestin in the gerbil OHCs by measuring their nonlinear capacitance (NLC). The average charge density (22,608 μm-2) measured was four times the average IMP density (5686 μm-2) reported in the freeze-fracture study. This suggests that each IMP contains four prestin molecules, based on the general notion that each prestin transfers a single elementary charge. We subsequently compared the voltage dependency and the values of slope factor of NLC and somatic motility simultaneously measured from the same OHCs to determine whether NLC and motility are fully coupled and how prestin subunits function within the tetramer. We showed that the voltage dependency and slope factors of NLC and motility were not statistically different, suggesting that NLC and motility are fully coupled. The fact that the slope factor is the same between NLC and motility suggests that each prestin monomer in the tetramer is in parallel, each interacting independently with cytoplasmic or other partners to facilitate the mechanical response.
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U2 - 10.1016/j.brainres.2010.03.070
DO - 10.1016/j.brainres.2010.03.070
M3 - Article
C2 - 20347723
AN - SCOPUS:77952104950
VL - 1333
SP - 28
EP - 35
JO - Brain Research
JF - Brain Research
SN - 0006-8993
ER -