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    University - Student Department: Chemistry Position: Graduate

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All Publications

  • Mapping the nanoscale organization of the human cell surface proteome reveals new functional associations and surface antigen clusters. bioRxiv : the preprint server for biology Floyd, B. M., Schmidt, E. L., Till, N. A., Yang, J. L., Liao, P., George, B. M., Flynn, R. A., Bertozzi, C. R. 2025

    Abstract

    The cell surface is a dynamic interface that controls cell-cell communication and signal transduction relevant to organ development, homeostasis and repair, immune reactivity, and pathologies driven by aberrant cell surface phenotypes. The spatial organization of cell surface proteins is central to these processes. High-resolution fluorescence microscopy and proximity labeling have advanced studies of surface protein associations, but the spatial organization of the complete surface proteome remains uncharted. In this study, we systematically mapped the surface proteome of human T-lymphocytes and B-lymphoblasts using proximity labeling of 85 antigens, identified from over 100 antibodies tested for binding to surface-exposed proteins. These experiments were coupled with an optimized data-independent acquisition mass spectrometry workflow to generate a robust dataset. Unsupervised clustering of the resulting interactome revealed functional modules, including well-characterized complexes such as the T-cell receptor and HLA class I/II, alongside novel clusters. Notably, we identified mitochondrial proteins localized to the surface, including the transcription factor TFAM, suggesting previously unappreciated roles for mitochondrial proteins at the plasma membrane. A high-accuracy machine learning classifier predicted over 6,000 surface protein associations, highlighting functional associations such as IL10RB's role as a negative regulator of type I interferon signaling. Spatial modeling of the surface proteome provided insights into protein dispersion patterns, distinguishing widely distributed proteins, such as CD45, from localized antigens, such as CD226 pointing to active mechanisms of regulating surface organization. This work provides a comprehensive map of the human surfaceome and a resource for exploring the spatial and functional dynamics of the cell membrane proteome.

    View details for DOI 10.1101/2025.02.12.637979

    View details for PubMedID 40027624

    View details for PubMedCentralID PMC11870420

  • Directed evolution of genetically encoded LYTACs for cell-mediated delivery. Proceedings of the National Academy of Sciences of the United States of America Yang, J. L., Yamada-Hunter, S. A., Labanieh, L., Sotillo, E., Cheah, J. S., Roberts, D. S., Mackall, C. L., Bertozzi, C. R., Ting, A. Y. 2024; 121 (13): e2320053121

    Abstract

    Lysosome-targeting chimeras (LYTACs) are a promising therapeutic modality to drive the degradation of extracellular proteins. However, early versions of LYTAC contain synthetic glycopeptides that cannot be genetically encoded. Here, we present our designs for a fully genetically encodable LYTAC (GELYTAC), making our tool compatible with integration into therapeutic cells for targeted delivery at diseased sites. To achieve this, we replaced the glycopeptide portion of LYTACs with the protein insulin-like growth factor 2 (IGF2). After showing initial efficacy with wild-type IGF2, we increased the potency of GELYTAC using directed evolution. Subsequently, we demonstrated that our engineered GELYTAC construct not only secretes from HEK293T cells but also from human primary T-cells to drive the uptake of various targets into receiver cells. Immune cells engineered to secrete GELYTAC thus represent a promising avenue for spatially selective targeted protein degradation.

    View details for DOI 10.1073/pnas.2320053121

    View details for PubMedID 38513100

  • Directed Evolution of Genetically Encoded LYTACs for Cell-Mediated Delivery. bioRxiv : the preprint server for biology Yang, J. L., Yamada-Hunter, S. A., Labanieh, L., Sotillo, E., Cheah, J. S., Roberts, D. S., Mackall, C. L., Ting, A. Y., Bertozzi, C. R. 2023

    Abstract

    Lysosome-targeting chimeras (LYTACs) are a promising therapeutic modality to drive the degradation of extracellular proteins. However, early versions of LYTAC contain synthetic glycopeptides that cannot be genetically encoded. Here we present our designs for a fully genetically encodable LYTAC (GELYTAC), making our tool compatible with integration into therapeutic cells for targeted delivery at diseased sites. To achieve this, we replaced the glycopeptide portion of LYTACs with the protein insulin like growth factor 2 (IGF2). After showing initial efficacy with wild type IGF2, we increased the potency of GELYTAC using directed evolution. Subsequently, we demonstrated that our engineered GELYTAC construct not only secretes from HEK293T cells but also from human primary T-cells to drive the uptake of various targets into receiver cells. Immune cells engineered to secrete GELYTAC thus represent a promising avenue for spatially-selective targeted protein degradation.

    View details for DOI 10.1101/2023.11.14.567117

    View details for PubMedID 38014030

    View details for PubMedCentralID PMC10680704