The transmembrane inner ear (TMIE) protein is required for the function of auditory and vestibular hair cells in the inner ear. Mutations in TMIE cause deafness in humans (DFNB6) and previous work in mice suggests a role for TMIE in mechanotransduction (i.e. the conversion of mechanical energy into electrical signals). While we know that TMIE is essential for the mechanotransduction process, it is not clear whether it is more of an accessory protein of the mechanotransduction complex or whether it plays a more central role in this process. To address questions about the function of Tmie, we characterized two zebrafish tmie mutants: a previously published null mutant (ru1000) and an uncharacterized mutant expressing a truncated version of Tmie (jp060). In addition we examined Tmie’s relationship with other known components of the mechanotransduction complex in hair cells (Lhfpl5a, Pcdh15a, Tmc2b), and we examined the function of various motifs that are present in Tmie. Both tmieru1000 and tmiejp060 mutants have normal hair-cell morphology and Lhfpl5a, Pcdh15a and Tmc2b are present in hair bundles where transduction takes place. Tmie itself localizes independently of other transduction proteins. However, our preliminary evidence using a yeast two-hybrid assay suggests that Tmie can interact directly with the tip-link protein Pcdh15a. In jp060 mutants, the truncation of Tmie, which eliminates the C-terminus of Tmie, results in a hypomorphic phenotype, with scant yet residual activity in hair cells. Consistent with the requirement of this region for the normal function of Tmie, the absence of the C-terminus abolishes the interaction with Pcdh15a in the two-hybrid experiments. Aside from potential interactions with Pcdh15a, we suspect that the lysine-rich C-terminus also interacts with phospholipids in the plasma membrane. Further inspection of other motifs in Tmie revealed that the first transmembrane domain, which is not conserved between fish and mammals at the amino acid level, is non-essential. However, the highly conserved second transmembrane is critical for stability and localization of Tmie at the site of mechanotransduction. Future experiments will include additional structure-function analysis to identify regions and residues critical to function, and yeast two-hybrid experiments to confirm and identify interacting partners of Tmie.