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Gee M, Atai K, Coller HA, Yeates TO, Castells-Graells R. Designed fluorescent protein cages as fiducial markers for targeted cell imaging. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582585. [PMID: 38464160 PMCID: PMC10925312 DOI: 10.1101/2024.02.28.582585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Understanding how proteins function within their cellular environments is essential for cellular biology and biomedical research. However, current imaging techniques exhibit limitations, particularly in the study of small complexes and individual proteins within cells. Previously, protein cages have been employed as imaging scaffolds to study purified small proteins using cryo-electron microscopy (cryo-EM). Here we demonstrate an approach to deliver designed protein cages - endowed with fluorescence and targeted binding properties - into cells, thereby serving as fiducial markers for cellular imaging. We used protein cages with anti-GFP DARPin domains to target a mitochondrial protein (MFN1) expressed in mammalian cells, which was genetically fused to GFP. We demonstrate that the protein cages can penetrate cells, are directed to specific subcellular locations, and are detectable with confocal microscopy. This innovation represents a milestone in developing tools for in-depth cellular exploration, especially in conjunction with methods such as cryo-correlative light and electron microscopy (cryo-CLEM).
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Affiliation(s)
- Morgan Gee
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA 90095
| | - Kaiser Atai
- Molecular Biology Interdepartmental Doctoral Program, University of California, Los Angeles, Los Angeles, CA, USA 90095
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, USA 90095
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA 90095
| | - Hilary A Coller
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, USA 90095
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA 90095
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, USA 90095
| | - Todd O Yeates
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA 90095
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, USA 90095
- UCLA-DOE Institute for Genomics and Proteomics, Los Angeles, CA, USA 90095
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