Effects of Mutation in the Conserved GTSRH Sequence of the Motor Protein Prestin on Its Characteristics

Prestin is a motor protein responsible for the outer hair cell (OHC) electromotility which amplifies the vibration of the organ of Corti in the inner ear. Identification of the functional significance of particular amino acids is necessary to characterize prestin. In this study, an attempt was made to clarify the role of the GTSRH sequence at positions 127-131 in prestin conserved in six proteins of the solute carrier (SLC) 26 family of which prestin is a member. To elucidate what role that sequence plays in the characteristics of prestin, mutations were introduced into the sequence and the characteristics of the constructed point mutants were investigated by Western blotting, immunofluorescence experiments and the whole-cell patch-clamp technique. The localization of T128A was altered, the anion transport function of H131A and that of S129T were lost and such functions of G127A, T128A, S129A and R130A declined. These results suggest that the GTSRH sequence plays an important role in the localization of prestin, as well as in its anion transport function.