Prestin is a specialized membrane motor protein central to the function of the auditory system, and particularly vital for sharp hearing in mammals. It is located within the organ of Corti, the crucial sensory structure inside the cochlea of the inner ear. The distribution and function of prestin offer deep insights into the biomechanical processes behind sound amplification and perception.

Location of Prestin in the Organ of Corti

Prestin is specifically found in the outer hair cells (OHCs) of the organ of Corti. Among the various cell types in the organ—such as inner hair cells, phalangeal cells, and supporting cells—only the outer hair cells express prestin in their lateral plasma membranes.testbook+3

• Outer hair cells are arranged in three rows along the cochlea, parallel to the basilar membrane.

• Prestin’s location in the lateral membrane of these cells is crucial for its action as a direct voltage-to-force converter, underpinning rapid cellular motility with microsecond precision.

Function of Prestin in Hearing

Prestin enables outer hair cells to change their length (contract and expand) in response to changes in the cell’s membrane potential. This electromotility:

• Amplifies the movement of the basilar membrane triggered by sound wave vibrations.

• Sharply tunes cochlear frequency selectivity, improving the ear’s ability to distinguish subtle differences in pitch and volume.

• Increases the sensitivity of hearing, ensuring the mammalian auditory system is capable of detecting even faint sounds.

By contracting and expanding in tandem with sound-induced voltage changes, prestin helps outer hair cells actively pump mechanical energy back into the cochlear partition, a process known as cochlear amplification.nature+1

Cell Types in the Organ of Corti

• Inner hair cells: Convert mechanical sound vibrations into electrical signals but do not contain prestin.

• Inner and outer phalangeal cells: Supporting cells for hair cells; they lack prestin.

• Outer hair cells: The only cells with prestin, acting as motor cells that fine-tune cochlear mechanics.

Table: Organ of Corti Cell Types and Prestin Expression

Clinical and Research Significance

Advances in auditory neuroscience show that defects in prestin function or expression can lead to hearing loss and frequency discrimination problems. Prestin is being explored for its role in noise-induced hearing damage and age-related cochlear dysfunction.nature

Conclusion and Answer

Prestin is found in the outer hair cells of the organ of Corti.

Thus, the correct answer is:

(3) Outer hair cells