The β subunit of the AP-1 complex is essential for hair cell function and basolateral targeting of NKA

Mechanosensation in hair cells relies on precise protein trafficking and specialized structures for proper function. Using zebrafish models, this work examines the role of adaptor protein 1 beta 1 (ap1b1) in mechanotransduction and ion regulation, showing that ap1b1 mutations mislocalize Na⁺/K⁺ ATPase and disrupt intracellular Na⁺ homeostasis. Additionally, we identify tmhsa and Tmc2a as key contributors to mechanotransduction. Tmhsa localizes to stereocilia tips and rescues auditory and vestibular defects in mutants, while Tmc2a modulates mechanosensitivity through distinct N- and C-terminal domains. These findings reveal critical mechanisms underlying hair-cell function and sensory system development.