Microscopy from Scientific Research

Diverse multiscale data can help decipher the highly complex cellular environments observed in 3DEM images. Fluorescence microscopy (FM)8 and ultrastructure expansion microscopy (U-ExM)9 can localize specific proteins to subregions of cells and organelles. Soft X-ray tomography (SXT)10 provides complementary visualization of 3D organelle architecture in frozen cells.11 Co-expression12 and cross-linking mass spectrometry (XL/MS) may aid in identifying macromolecular complexes and modeling their interactions. Mass spectrometry (MS) proteomics yields a vast amount of information on the proteins present in a cell or isolated organelle, and AI-based methods such as AlphaFold2 (AF2) can predict structures for these catalogs of proteins. Single-particle analysis (SPA) of isolated components can yield both structural insights and the means to find these structures in cryo-ET data by template matching (structure shown: dimeric photosystem I supercomplex, PDB: 7ZQD). Molecular interactions can further be detected within the cellular environment by proximity labeling.13 All example data comes from C. reinhardtii. Sources of the images: (A, left) courtesy of George Witman; (A, right) courtesy of Travis Walton and Alan Brown (CC BY 4.0); (B, left) courtesy of Ron Kelly, Alexander Rigort, and Abhay Kotecha; (C, FM) courtesy of Martin Jonikas (CC BY 4.0); (C, U-ExM) courtesy of Paul Guichard and Virginie Hamel; (C, SXT) courtesy of Benedikt Westermann (CC BY 3.0).

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