Linear ubiquitination triggers Amph-mediated T-tubule biogenesis

. Loss of LUBEL leads to Amphiphysin (Amph)-positive membrane sheets instead of tubular networks. The ubiquitin ligase activity of LUBEL and direct interaction with Amph, a BAR domain protein involved in membrane tubulation, are crucial for proper T-tubule morphology. LUBEL and M1-linked ubiquitin chains assemble into puncta on membranes through multivalent interactions, facilitating Amph-mediated tubulation. Notably, the Amph-LUBEL/RNF31 interaction is evolutionarily conserved across species, underscoring a fundamental role for linear ubiquitination in membrane remodeling. Our findings uncover an unexpected function of linear ubiquitination in membrane deformation driven by BAR proteins.