TRIOBP (TRIO and F-actin binding protein) encodes multiple protein isoforms that play crucial roles in actin cytoskeleton organization and stabilization. The gene produces distinct isoforms with specialized functions: TRIOBP-1 is a ubiquitously expressed protein that binds F-actin and prevents its depolymerization, important for cell cycle regulation, adhesion junctions, and neuronal differentiation 1. TRIOBP-4 is highly specialized for inner ear function, bundling actin in stereocilia and being essential for hearing 1. TRIOBP-5 localizes to stereocilia rootlets where it bundles rootlet F-actin and works with ANKRD24 to anchor stereocilia into the cuticular plate 2. The protein interacts with cardiac hERG channels, regulating surface expression and affecting cardiac excitability 3. TRIOBP mutations cause autosomal recessive nonsyndromic hearing loss (DFNB28) through disruption of stereocilia structure 1. Beyond hearing disorders, TRIOBP variants are associated with schizophrenia through protein aggregate formation, various cancers, pulmonary fibrosis where it promotes fibroblast-to-myofibroblast transition 4, and potentially primary open-angle glaucoma and kidney stone disease 56. The protein's diverse isoforms enable tissue-specific functions while maintaining core actin-regulatory capabilities.