Espin (protein)

Espin is a protein that in humans is encoded by the ESPIN gene. Espin is an actin-bundling protein that plays a crucial role in the organization of actin filaments in cells, particularly in the stereocilia of the inner ear and hair cells. Mutations in the ESPIN gene can lead to deafness due to the disruption of the stereocilia's structure and function.

Structure

Espin is a multifunctional actin-bundling protein that contains multiple actin-binding sites and Whirlin-binding sites. The protein is composed of an ankyrin repeat domain, a proline-rich domain, and a carboxy terminus that is responsible for actin-bundling activity. The ankyrin repeat domain is involved in protein-protein interactions, while the proline-rich domain is thought to interact with SH3 domain-containing proteins.

Function

Espin is involved in the elongation and maintenance of the stereocilia in the inner ear and hair cells. It bundles actin filaments, which are essential for the structure and function of the stereocilia. The protein also interacts with Whirlin, a scaffolding protein, to regulate the length and width of the stereocilia. In addition, Espin is involved in the formation of microvilli in intestinal epithelial cells.

Clinical significance

Mutations in the ESPIN gene can cause autosomal recessive non-syndromic hearing loss. These mutations disrupt the structure and function of the stereocilia, leading to deafness. Some mutations can also cause auditory neuropathy, a condition characterized by a disruption in the transmission of sound signals from the inner ear to the brain.

See also

• Actin
• Stereocilia
• Deafness
• Ankyrin repeat
• Proline
• SH3 domain
• Whirlin
• Microvilli
• Intestinal epithelial cell
• Autosomal recessive
• Auditory neuropathy