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Updated: Sep 16, 2025

Reconstitution of Msp1 Extraction Activity with Fully Purified Components
Published on: August 10, 2021
Molecular Determinants of TMC Protein Biogenesis and Trafficking
Dedong Shao1, Jinru Tan1, Xiaozhi Fan1
1State Key Laboratory of Brain Function and Disorders, MOE Frontiers Center for Brain Science, Institutes of Brain Science, ENT Institute and Otorhinolaryngology Department of Eye & ENT Hospital, Fudan University, Shanghai 200032, China.
Abstract:
Transmembrane channel-like (TMC) proteins are essential for hearing and balance; however, the molecular mechanisms that regulate their proper folding and membrane targeting remain poorly understood. Here, we establish Caenorhabditis elegans as a genetically tractable model to dissect TMC-1 trafficking by combining CRISPR knock-in strains, super-resolution microscopy, and genome-wide forward genetic screening. We show that TMC-1 robustly localizes to the plasma membrane in both neurons and muscle cells and identify a conserved valine (V803) in transmembrane domain 9 (TM9) as critical for its biogenesis and trafficking. Structural analyses guided by AlphaMissense and AlphaFold uncover two evolutionarily conserved functional hotspots, one in the extracellular loop adjacent to TM9 and the other in the TMC signature motif, which are interconnected by an evolutionarily conserved disulfide bond. Disrupting this bond in worm TMC-1 abolishes its cell-surface localization and destabilizes the mechanotransduction channel complex. Together, these findings provide a structural framework for interpreting deafness-causing mutations in human TMC1 and highlight disulfide-bond-linked hotspots as key molecular determinants of TMC protein biogenesis and trafficking.
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