Espin (ESPN)

ESPN encodes a multifunctional actin-bundling protein. It plays a major role in regulating the organization, dimensions, dynamics, and signaling capacities of the actin filament-rich, microvillus-type specializations that mediate sensory transduction in various mechanosensory and chemosensory cells. Mutations in this gene are associated with autosomal recessive neurosensory deafness, and autosomal dominant sensorineural deafness without vestibular involvement. The human protein shares 83% and 86% sequence identity with the mouse and rat homologs, respectively. PCR analysis of human fetal inner ear cDNA revealed expression of ESPN in the inner ear. ESPN expression constructs lacking either one or both of the actin-binding sites were unable to crosslink actin filaments when transfected into BHK fibroblasts.