biostudies-literatureAuvray MNIGMS NIH HHSMax-Planck-Gesellschaft11107https://www.ebi.ac.uk/biostudies/studies/S-EPMC12701065biostudies-literatureUnknown16(1)Fluorescent probes enable precise visualization of dynamic cellular processes, especially when combined with super-resolution imaging techniques that overcome the diffraction limit. However, traditional labeling strategies, including fluorescent protein fusions (e.g., GFP) or ligand-linked fluorophores, often perturb protein function or induce biological side effects. Here, we report a covalent fluorescent probe for endogenous tubulin, a key cytoskeletal protein governing cell division, motility, and intracellular transport. Using cabazitaxel as a tubulin targeting moiety and silicon-rhodamine as a cell permeable fluorophore, we designed and optimized probe, 6-SiR-o-C₉-CTX, containing a biocompatible cleavable linker with a sulfonium center. It exhibits cell permeability, fluoroNature communicationsBiocompatible sulfonium-based covalent probes for endogenous tubulin fluorescence nanoscopy in live and fixed cells.PMC12701065R01 GM129325Auvray MDybkov OLukinavicius GUrlaub HKoenen TfalseBiocompatible sulfonium-based covalent probes for endogenous tubulin fluorescence nanoscopy in live and fixed cells.Fluorescent probes enable precise visualization of dynamic cellular processes, especially when combined with super-resolution imaging techniques that overcome the diffraction limit. However, traditional labeling strategies, including fluorescent protein fusions (e.g., GFP) or ligand-linked fluorophores, often perturb protein function or induce biological side effects. Here, we report a covalent fluorescent probe for endogenous tubulin, a key cytoskeletal protein governing cell division, motility, and intracellular transport. Using cabazitaxel as a tubulin targeting moiety and silicon-rhodamine as a cell permeable fluorophore, we designed and optimized probe, 6-SiR-o-C₉-CTX, containing a biocompatible cleavable linker with a sulfonium center. It exhibits cell permeability, fluoro2025-01-01T00:00:00Z2025 Dec2026-06-06T02:59:55.966Z2026-05-25T03:07:53.304ZS-EPMC127010654138148510.1038/s41467-025-67319-x