Project Summary In this proposal we hope to build on our efforts defining the cryoEM structure of prestin, the OHC lateral wall motor responsible for cochlear amplification, in the depolarized and contracted state. In this proposal we seek to define the protein's structure in the expanded state brought about by voltage. We will use complementary methods to determine its structure exploiting recent advances in image processing and using temperature and mutations that affect its violtage sensitivity. In addition, we will also be using modeling using molecular dynamics simulations to understand its structure under voltage control.