Hearing’s Key Protein Identified

After more than a decade of study and many false leads, researchers have identified the key protein in the ear that translates sound into electrical signals that can be understood by the brain.

“This is the most important molecule in the ear,” said neurobiologist Peter Gillespie of the Oregon Health & Science University. “Identifying it is getting at the real kernel of how the inner ear works.”

The protein, called TRPA1, sits at the tip of the specialized hairs, called cilia, in the inner ear, a team headed by neurobiologist David Corey of Harvard Medical School reported in this week’s issue of the journal Nature.

The doughnut-shaped protein has a passage through its center that, when open, permits potassium and calcium ions to flood into the cell. Those ions carry a positive charge that generates an electrical signal that is relayed to the brain.

Through biological and mechanical mechanisms, vibrations of the cilia are transmitted to TRPA1. Each vibration of a hair causes the channel to open and close. The frequency of the sound waves thereby generates an electrical signal of the same frequency.

Corey noted that defects in other components of this so-called transduction apparatus are known to cause deafness, and faults in this protein may do so as well.